Monsters

A monster’s statistics, sometimes referred to as its stat block, provide the essential information that you need to run the monster.

Size

A monster can be Diminutive, Tiny, Small, Medium, Large, Huge, or Gargantuan. The Size Categories table shows how much space a creature of a particular size controls in combat. See the Core Rules for more information on creature size and space.

Type

A monster’s type speaks to its fundamental nature. Certain spells, magic items, class features, and other effects in the game interact in special ways with creatures of a particular type. For example, an arrow of dragon slaying deals extra damage not only to dragons but also other creatures of the dragon type, such as dragon turtles and wyverns.

The game includes the following monster types, which have no rules of their own.

Aberrations are utterly alien beings. Many of them have innate magical abilities drawn from the creature’s alien mind rather than the mystical forces of the world. The quintessential aberrations are the twisted comiedai, mkhulu, and Awakened corruptions.

Beasts are non-humanoid creatures that are a natural part of the fantasy ecology. Some of them have magical powers, but most are unintelligent and lack any society or language. Beasts include all varieties of ordinary animals, dinosaurs, and giant versions of animals.

Celestials are creatures of the Astral who are acting on behalf of an Ascendant or deity. They might be employed as messengers or agents in the mortal realm and throughout the planes.

Constructs are made, not born. Some are programmed by their creators to follow a simple set of instructions, while others are imbued with sentience and capable of independent thought. Golems are the iconic constructs.

Dragons are large reptilian creatures of ancient origin and tremendous power. True dragons, including the good metallic dragons and the evil chromatic dragons, are highly intelligent and have innate magic. Also in this category are creatures distantly related to true dragons, but less powerful, less intelligent, and less magical, such as wyverns and pseudo-dragons.

Elementals are creatures native to the elemental planes. Some creatures of this type are little more than animate masses of their respective elements, including the creatures simply called elementals. Others have biological forms infused with elemental energy. The races of genies, including djinn and efreet, form the most important civilizations on the elemental planes. Other elemental creatures include azers, invisible stalkers, and water weirds.

Fey are magical creatures closely tied to the forces of nature, called the kami. They dwell in twilight groves and misty forests. In some worlds, they are closely tied to the Plane of Shadow, also called the Plane of Faerie. Fey are most often obsessed with something mortal, called their aspect. Fey include dryads, pixies, and satyrs.

Fiends are creatures of either the Astral or Abyssal, summoned into the Mortal in various horrifying forms. A few are the servants of deities, but many more labor under the leadership of arch-devils and demon princes. Evil priests and mages sometimes summon fiends to the material world to do their bidding. Fiends include demons, devils, hell hounds, and other lesser creatures.

Giants tower over humans and their kind. They are human-like in shape, though some have multiple heads (ettins) or deformities (fomorians). The six varieties of true giant are hill giants, stone giants, frost giants, fire giants, cloud giants, and storm giants. Besides these, creatures such as ogres and trolls are giants.

Humanoids are the main peoples of a fantasy gaming world, both civilized and savage, including humans and a tremendous variety of other species. They have language and culture, few if any innate magical abilities (though most humanoids can learn spellcasting), and a bipedal form. The most common humanoid races are the ones most suitable as player characters: humans, dwarves, elves, and halflings. Almost as numerous are the races of goblinoids (goblins, hobgoblins, and bugbears), orcs, lizardfolk, and kobolds.

Monstrosities are monsters in the strictest sense—frightening creatures that are not ordinary, not truly natural, and almost never benign. Some are the results of magical experimentation gone awry and others are the product of terrible curses. They defy categorization, and in some sense serve as a catch-all category for creatures that don’t fit into any other type.

Oozes are gelatinous creatures that rarely have a fixed shape. They are mostly subterranean, dwelling in caves and dungeons and feeding on refuse, carrion, or creatures unlucky enough to get in their way. Black puddings and gelatinous cubes are among the most recognizable oozes.

Plants in this context are vegetable creatures, not ordinary flora. Most of them are ambulatory, and some are carnivorous. The quintessential plants are the shambling mound and the treant. Fungal creatures such as the gas spore and the myconid also fall into this category.

Undead are once-living creatures brought to a horrifying state of undeath through the practice of necromantic magic or some unholy curse, generally involving the entropy spirits called jotnar. Undead include walking corpses, such as vampires and zombies, as well as bodiless spirits, such as ghosts and specters.

Tags

A monster might have one or more tags appended to its type, in parentheses. For example, an orc has the humanoid (orc) type. The parenthetical tags provide additional categorization for certain creatures. The tags have no rules of their own, but something in the game, such as a magic item, might refer to them. For instance, a spear that is especially effective at fighting demons would work against any monster that has the demon tag.

Attitude

Monsters have an attitude listed next to their size and type (e.g. Large beast, craven;) that describes how a generic member of that type of monster will act by default. Specific individuals may act differently, but this serves as a guide to role play for the GM. Example attitudes:

Craven. A craven creature is easy to intimidate into fleeing (if possible) or surrendering (if flight is too risky). They tend to attack in groups and run when casualties start to mount or if their leader is killed.

Fearless. Fearless monsters are immune to morale checks. While not totally single-minded, they generally are resistant to mental manipulation.

Guardian. Guardian monsters have either been trained to protect their masters or are naturally inclined to protect their fellows/allies. Usually combined with domestic. Guardian animals act as lookouts and will aggressively intervene in attempts to attack their protected allies.

Domestic. Domesticated monsters are particularly apt to be used as beasts of burden, mounts, work animals, and pets. In general, they will avoid fighting unless trained as a guard animal, and can be easily soothed with Animal Handling checks.

Herd Mentality. Herd animals are a mix of pack animals and craven. they operate together, and if one fights they all fight; if one flees, the rest will stampede as well.

Honorable. These creatures will generally honor bargains, parole, and challenges to duels. Even evil creatures can be honorable. Most honorable creatures can be reasoned with.

Individualistic. Every monster for themselves. These tend to live alone or, if the are encountered in groups, not really care about the other members of their groups. Killing one doesn’t affect a different one, but an individual might flee if wounded even if it shatters the group’s chances.

Group/Pack Mentality. The opposite of being Individualistic. These bond to their pack and will protect them, up to sacrificing themselves for other members of their pack.

Single-minded. Oozes, zombies, and some other creatures are single-minded. This means that they generally cannot be reasoned with, distracted, confused, or intimidate. They will not flee or surrender. Generally they will pursue the closest target in combat; if given other orders they will do those to the exclusion of all else, including personal safety.

Armor Class

A monster that wears armor or carries a shield usually has an Armor Class (AC) that takes its armor, shield, and Dexterity into account. Otherwise, a monster’s AC is based on its Dexterity modifier and natural armor, if any, but may include other modifiers to have the appropriate fictional and mechanical behavior. If a monster has natural armor, wears armor, or carries a shield, this is noted in parentheses after its AC value.

Hit Points

A monster usually dies or is destroyed when it drops to 0 hit points. For more on hit points, see .

A monster’s hit points are presented both as a die expression and as an average number. For example, a monster with 2d8 hit points has 9 hit points on average (2 4½).

A monster’s size determines the die used to calculate its hit points, as shown in the Hit Dice by Size table.

Hit Dice by Size

A monster’s Constitution modifier also affects the number of hit points it has. Its Constitution modifier is multiplied by the number of Hit Dice it possesses, and the result is added to its hit points. For example, if a monster has a Constitution of 12 (+1 modifier) and 2d8 Hit Dice, it has 2d8 + 2 hit points (average 11).

Speed

A monster’s speed tells you how far it can move on its turn. For more information on speed, see .

All creatures have a walking speed, simply called the monster’s speed. Creatures that have no form of ground-based locomotion have a walking speed of 0 feet.

Some creatures have one or more of the following additional movement modes.

Burrow

A monster that has a burrowing speed can use that speed to move through sand, earth, mud, or ice. A monster can’t burrow through solid rock unless it has a special trait that allows it to do so. Burrowing out of reach provokes opportunity attacks. Burrowing doesn’t leave a usable tunnel behind it unless the monster has a special trait that says otherwise (such as the purple worm).

Climb

A monster that has a climbing speed can use all or part of its movement to move on vertical surfaces. The monster doesn’t need to spend extra movement to climb. Monsters generally do still need a free hand to climb unless they have an ability such as Spider Climb that says otherwise.

Fly

A monster that has a flying speed can use all or part of its movement to fly. Some monsters have the ability to hover, which makes them hard to knock out of the air (as explained in the rules on flying in the core rules). Such a monster stops hovering when it dies.

Swim

A monster that has a swimming speed doesn’t need to spend extra movement to swim. They are also immune to any of the penalties of fighting underwater (such as disadvantage on melee attacks, etc.).

Ability Scores and Saving Throws

Every monster has six ability scores (Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma). If a monster has a bonus to a saving throw, it is listed in the saving throws section. If a save isn’t listed, the saving throw modifiers are equal to the ability scores.

Morale

Monsters, unlike PCs, can be by effects that shake them enough emotionally. When the GM decides that a non-legendary monster may not be able to continue a combat for reasons other than being reduced to zero hit points (or outright killed), they will generally make a Morale save for that creature. This is a Wisdom saving throw. The first save usually has a DC of 10; particularly dramatic events may require beating a DC of 15 to succeed. On a failed save, the creature gains the condition until conditions materially change or the end of their next turn, whichever lasts longer.

Triggering a Morale Save. Here are some conditions that might (depending on the fiction) trigger a Morale Save.

• A hunting predator becoming (unless it is defending its nest or magically compelled).
• A common warrior (guard, goblin raider, etc.) seeing their leader get taken out.
• A common warrior seeing a bunch of their allies killed in a single turn (such as by a powerful area of effect ability).
• One of their more powerful allies being downed in a single turn.
• Powerful supernatural or monstrous fear effects against normal people.
• A powerful intimidation attempt or offer of surrender when already on the edge.

Recovering from Being Broken. A few possible circumstances that may trigger a recovery from being broken:

• A powerful enemy being reduced to zero hit points.
• A rousing speech by a leader they trust.
• A supernatural intervention on their side (such as a demon being summoned to reinforce cultists)
• Reinforcements or news of a victory elsewhere.

Additional Bonuses

Monsters do not have a proficiency bonus like player characters. Instead, they have an arbitrary additional bonus that affects selected ability checks, attack rolls, saving throw DCs, and saving throw modifiers. These are generally in the range of +0 — +6 like proficiency bonuses, but are applied to make the numbers come out right while also representing the agility, grace, and training of the monster in question. Clumsy monsters or those who are not generally predatory frequently have no additional bonus beyond their raw ability score to attack rolls, for instance, while highly skilled combatants might get a similar bonus to a player character’s proficiency, and many monsters may be in between the two. As a rule of thumb, use the offensive rating as the character level when determining the maximum additional bonus to apply.

Skills

The Skills entry is reserved for monsters that are exceptionally competent in one or more skills. For example, a monster that is very perceptive and stealthy might have bonuses to Wisdom (Perception) and Dexterity (Stealth) checks.

A skill bonus is usually the sum of a monster’s relevant ability modifier and its additional bonus, if any. Other modifiers might apply. For instance, a monster might have a larger-than-expected bonus (usually double its additional bonus) to account for its heightened expertise.

Vulnerabilities, Resistances, and Immunities

Some creatures have vulnerability, resistance, or immunity to certain types of damage. In addition, some creatures are immune to certain conditions. Immunity to a condition such as poisoned does not imply immunity to a matching damage type. The reverse is also not implied—immunity to poison damage does not imply resistance or immunity to the poisoned condition.

Senses

The Senses entry notes a monster’s passive Wisdom (Perception) score, as well as any special senses the monster might have. Special senses are described below.

Blindsight

A monster with blindsight can perceive its surroundings without relying on sight, within a specific radius. For all purposes this counts as being able to see within that radius. Creatures without eyes, such as grimlocks and gray oozes, typically have this special sense, as do creatures with echolocation or heightened senses, such as bats and true dragons. If a monster is naturally blind other than its blindsight, it has a parenthetical note to this effect, indicating that the radius of its blindsight defines the maximum range of its perception.

Darkvision

A monster with darkvision can see in the dark within a specific radius. The monster can see in dim light within the radius as if it were bright light, and in darkness as if it were dim light. The monster can’t discern color in darkness, only shades of gray. Many creatures that live underground have this special sense.

Tremorsense

A monster with tremorsense can detect and pinpoint the origin of vibrations within a specific radius, provided that the monster and the source of the vibrations are in contact with the same ground or substance. Tremorsense can’t be used to detect flying or incorporeal creatures. Many burrowing creatures, such as ankhegs and umber hulks, have this special sense. Tremorsense does not count as sight.

Truesight

A monster with truesight can, out to a specific range, see in normal and magical darkness, see invisible creatures and objects (completely negating the invisible condition with respect to that monster), automatically detect visual illusions and succeed on saving throws or ability checks against them, and perceive the original form of a shapechanger or a creature that is transformed by magic. Furthermore, the monster can see into the Ethereal Plane within the same range.

Armor, Weapon, and Tool Proficiencies

Assume that a creature is proficient with its armor and tools. If you swap them out, you decide whether the creature is proficient with its new equipment. Except in rare cases, monsters generally prefer to use weapons and armor suited for them. For example, a hill giant typically wears patchwork armor and wields a greatclub. You could equip a hill giant with chain mail and a greataxe instead, and assume the giant is proficient with both, one or the other, or neither. See the for rules on using armor without proficiency.

Monsters conditionally apply their additional bonus to attack rolls, as described above. This same bonus should apply to all attacks if it applies to any, and the game goes more smoothly if all relevant numeric bonuses are listed in the monster’s attack entry.

Languages

The languages that a monster can speak are listed in alphabetical order. Sometimes a monster can understand a language but can’t speak it, and this is noted in its entry. A “—” indicates that a creature neither speaks nor understands any language.

Telepathy

Telepathy is a magical ability that allows a monster to communicate mentally with another creature within a specified range. The contacted creature doesn’t need to share a language with the monster to communicate in this way with it, but it must be able to understand at least one language. A creature without telepathy can receive and respond to telepathic messages but can’t initiate or terminate a telepathic conversation. A creature in any location where magic doesn’t function can’t send or receive telepathic messages.

A telepathic monster doesn’t need to see a contacted creature and can end the telepathic contact at any time. The contact is broken as soon as the two creatures are no longer within range of each other or if the telepathic monster contacts a different creature within range. A telepathic monster can initiate or terminate a telepathic conversation without using an action, but while the monster is incapacitated, it can’t initiate telepathic contact, and any current contact is terminated.

Challenge

A monster’s challenge ratings tells you how great a threat the monster is. Each monster has two ratings, offensive and defensive, separated by a slash, written as offensive/defensive. Generally, the overall rating is the geometric mean of the two (the square root of the product of the values), but this really provides little relevant information.

Offensive Rating (OR). The offensive rating of a monster relative to the party level tells you how likely it is for that monster to drop a full-health character to 0 HP in a single round.

Defensive Rating (DR). The defensive rating of a monster tells you how likely it is for that monster to survive long enough under direct fire from the party’s primary damage dealers in order to do use its cool abilities at least once (generally considered about 3 rounds). This assumes baseline characters without substantial combat-effective magic items or particularly targeting vulnerabilities. It’s a rough static training dummy measure and should be taken with a grain of salt.

What is a baseline party? A baseline party makes the following assumptions.

• 4 player characters without combat-effective allies, summoned creatures, or pets.
• Standard array
• Characters built competently, but not particularly optimized for damage. Their highest ability scores are in their class primary attributes, their secondary attributes are not neglected, and they’re using equipment that suits their class abilities. ASIs are spent to improve the primary ability score until cap.
• Generally two of them are specialized damage dealers, with the other two playing any combination of support, healing, defensive, skills, or control.
• None of them have magic items that substantially improve their combat capabilities.

An example of such a party might be

• A sword-and-shield-using Defender Armsman
• A dual-wielding rogue
• A fire-loving Awakened Arcanist
• A Life-domain priest

Special Traits

Special traits (which appear after a monster’s challenge rating but before any actions or reactions) are characteristics that are likely to be relevant in a combat encounter and that require some explanation.

Spellcasting

A monster with the Spellcasting special trait has the ability to cast selected spells, which it uses to cast its spells (as explained in the Core Rules). The monster has a list of spells known, which may be drawn from multiple class lists. Each spell says how many times it can be cast per day.

Specific monsters have innate spellcasting which means that they do require components to cast their spells; they can still be perceived to be casting a spell.

Spell selection. Casters generally only have a limited selection of spells in their stat blocks, those focused on combat use. Generally they have a big concentration spell and one or more lower priority or defensive spells. Their primary spell damage comes from their spell attacks, which count as cantrips. Non-combat spells are at the discretion of the GM and should be chosen as appropriate for the fictional position of that particular caster.

Be wary of hard crowd control spells on high-Constitution casters. Hard crowd control spells are those that impose conditions such as stunned or paralyzed that completely deny PC turns. Many tables consider those un-fun since the affected party member cannot do anything. In addition, these spells and abilities can swing fights tremendously—landing one early on a key damage dealer or support character can mean a party’s total defeat while not landing it at all can result in a cakewalk fight. Effectively, these spells are extremely hard to judge as to effectiveness and produce wild swings in table experience. Soft crowd control such as isn’t nearly as swingy.

Actions

When a monster takes its action, it can choose from the options in the Actions section of its stat block or use one of the actions available to all creatures, such as the Dash or Hide action, as described in .

Melee and Ranged Attacks

The most common actions that a monster will take in combat are melee and ranged attacks. These can be spell attacks or weapon attacks, where the “weapon” might be a manufactured item or a natural weapon, such as a claw or tail spike. For more information on different kinds of attacks, see the Core Rules.

Creature vs. Target. The target of a melee or ranged attack is usually either one creature or one target, the difference being that a “target” can be a creature or an object.

Hit. Any damage dealt or other effects that occur as a result of an attack hitting a target are described after the “Hit;” notation. You have the option of taking average damage or rolling the damage; for this reason, both the average damage and the die expression are presented. Any effect listed in this portion takes place only if the attack hits. Only damage that doesn’t require an additional saving throw to take effect after a hit is doubled on a critical hit.

Miss. If an attack has an effect that occurs on a miss, that information is presented after the “Miss:” notation.

Spell Attacks

Some monsters have spell attacks. These count as cantrips for features for that care about spells. Generally, they do not require material components (but require one of verbal or somatic components unless specified otherwise) and are specialized for that creature.

Multiattack

A creature that can make multiple attacks on its turn has the Multiattack action. A creature can’t use Multiattack when making an opportunity attack, which must be a single melee attack. If the creature has the Multiattack ability, it specifies exactly which attacks may be made and in what combinations.

Ammunition

A monster carries enough ammunition to make its ranged attacks. You can assume that a monster has 5 pieces of ammunition for a thrown weapon attack, and 10 pieces of ammunition for a projectile weapon such as a bow or crossbow.

Reactions

If a monster can do something special with its reaction, that information is contained here. If a creature has no special reaction, this section is absent.

All creatures with a melee attack in their stat block can make opportunity attacks. Monsters cannot take the special actions outlined in . If they have similar capabilities, those will appear as explicit actions in their stat blocks.

Limited Usage

Some special abilities have restrictions on the number of times they can be used.

X/Day. The notation “X/Day” means a special ability can be used X number of times and that a monster must finish a long rest to regain expended uses. For example, “1/Day” means a special ability can be used once and that the monster must finish a long rest to use it again.

Recharge X-Y. The notation “Recharge X-Y” means a monster can use a special ability once and that the ability then has a random chance of recharging during each subsequent round of combat. At the start of each of the monster’s turns, roll a d6. If the roll is one of the numbers in the recharge notation, the monster regains the use of the special ability. The ability also recharges when the monster finishes a short or long rest.

For example, “Recharge 5-6” means a monster can use the special ability once. Then, at the start of the monster’s turn, it regains the use of that ability if it rolls a 5 or 6 on a d6.

Recharge after a Short or Long Rest. This notation means that a monster can use a special ability once and then must finish a short or long rest to use it again.

Grapple Rules for Monsters

Many monsters have special attacks that allow them to quickly grapple prey. When a monster hits with such an attack, it doesn’t need to make an additional ability check to determine whether the grapple succeeds, unless the attack says otherwise.

A creature grappled by the monster can use its action to try to escape. To do so, it must succeed on a Strength (Athletics) or Dexterity (Acrobatics) check against the escape DC in the monster’s stat block. If no escape DC is given, assume the DC is 10 + the monster’s Strength (Athletics) modifier.

Equipment

A stat block rarely refers to equipment, other than armor or weapons used by a monster. A creature that customarily wears clothes, such as a humanoid, is assumed to be dressed appropriately.

You can equip monsters with additional gear and trinkets however you like, and you decide how much of a monster’s equipment is recoverable after the creature is slain and whether any of that equipment is still usable. A battered suit of armor made for a monster is rarely usable by someone else, for instance. It’s normally rare for non-magical weapons used by monsters to have much value.

If a spellcasting monster needs material components to cast its spells, assume that it has the material components it needs to cast the spells in its stat block.

Variants

Some monsters have variant options, such as the acolyte having the cultist variant. Variants are listed in their own section and generally add traits or actions or modify the basic statistics. Each variant describes how it affects the challenge ratings of the monster when applied.

Legendary Creatures

A legendary creature can do things that ordinary creatures can’t. It can take special actions outside its turn, and it might exert magical influence for miles around. If a creature assumes the form of a legendary creature, such as through a spell, it doesn’t gain that form’s legendary actions, lair actions, or regional effects.

Legendary Actions

A legendary creature can take a certain number of special actions—called legendary actions—outside its turn. Only one legendary action option can be used at a time and only at the end of another creature’s turn. A creature regains its spent legendary actions at the start of its turn. It can forgo using them, and it can’t use them while incapacitated or otherwise unable to take actions. If surprised, it can’t use them until after its first turn in the combat.

A Legendary Creature’s Lair

A legendary creature might have a section describing its lair and the special effects it can create while there, either by act of will or simply by being present. Such a section applies only to a legendary creature that spends a great deal of time in its lair.

Lair Actions

If a legendary creature has lair actions, it can use them to harness the ambient magic in its lair. On initiative count 20 (losing all initiative ties), it can use one of its lair action options. It can’t do so while incapacitated or otherwise unable to take actions. If surprised, it can’t use one until after its first turn in the combat.

Customizing Monsters

There are many easy ways to customize the NPCs presented here for your home campaign.

Lineage and Cultural Traits. You can add lineage and cultural traits to an NPC (especially humanoids and giants). Adding racial traits to an NPC doesn’t alter its challenge rating. For more on lineage traits, see ; for more on cultural traits, see .

Spell Swaps. One way to customize an NPC spellcaster is to replace one or more of its spells. You can substitute any spell on the NPC’s spell list with a different spell of the same cost from any list. Swapping spells in this manner can an NPC’s challenge ratings.

Non-damaging spells and abilities and challenge ratings Damaging spells and abilities are fairly straightforward to apply to challenge rating. If they do more damage than the monster’s other damaging actions, include them in the best-3-rounds model. Done. Non-damaging ones are more difficult. Some suggestions include:

• If a spell or ability does not deal damage, imposes no conditions on an enemy, and does not serve a defensive purpose (by healing, reducing damage, buffing the creature or its allies, etc.), then it likely has no effect on either challenge rating. For example, giving a monster access to the cantrip doesn’t significantly change the combat difficulty.
• If a spell imposes negative conditions on an enemy, find a similar-targeted damaging spell with the same cost (or a monster ability from a similar-threat monster) and include it in the damage calculations. Conditions that dominate or completely disable an opponent (such as a banshee’s wail) are particularly strong and will generally increase offensive rating significantly.
• If a spell or ability serves a defensive purpose, and especially if it does not require a full action, increase the monster’s Defensive Rating by one. More may be warranted for particularly strong effects or those that cannot be overcome except by higher-level foes.
• It a spell has a long duration (ie > 10 minutes) and does not require concentration, assume that it has pre-cast that spell unless the monster is surprised. Include such things as directly in the stat block as a baseline.

Armor and Weapon Swaps. You can upgrade or downgrade an NPC’s armor, or add or switch weapons. Adjustments to Armor Class and damage can change an NPC’s challenge rating.

Magic Items. The more powerful an NPC, the more likely it has one or more magic items in its possession. An archmage, for example, might have a magic staff or wand, as well as one or more potions and scrolls. Giving an NPC a potent damage-dealing magic item could alter its offensive challenge rating.

Monster Math

Calculating Offensive Rating

Offensive Rating is determined by the following process:

1. Determine the most damaging three rounds the monster can do. If it has a recharge ability, assume that can be used once in those three rounds, or twice if it is Recharge (4-6) or more. Assume all attacks hit and deal average damage. Assume that abilities that hit an area (such as cones, lines, or circles), hit two creatures. If an ability requires a saving throw, assume that the affected targets fail. This is a worst-reasonable-case scenario, and should be treated as such. Include Legendary actions and damaging reactions, auras, etc.
2. Calculate the average damage per round over those three rounds.
3. Compare to the Offensive Rating table and find the matching rating. Note the attack bonus and saving throw modifier listed there.
4. Apply any listed adjustments. The most common is that if the creature’s attack bonus is two or more points higher than the attack bonus for the listed row, the overall offensive rating should be adjusted up by one step for every two points higher the attack bonus is. Similarly, if the attack bonus is lower than the listed value by two or more, decrease the offensive rating by one step for every two points of difference. If most of the monster’s damage comes from abilities that require saving throws, use that bonus instead of the attack bonus.
5. Play test. Averages don’t always tell the full story. If the monster has few attacks that each deal substantial damage, it will be more spiky (more liable to surprise-kill a character OR to fall flat and do nothing) than one that makes many smaller attacks. Higher number of dice do, however, also tend toward the average. 1d20 has a much broader distribution (being entirely flat) than 3d6+2, although the latter also has a higher floor (5 vs 1) and average (12.5 vs 10.5). The chances of rolling 20 damage on 1d20 is 1 in 20 (5%); on 3d6+2 it’s only 1 in 216 (0.46%).

The following table summarizes the relationship between Offensive Rating and damage output.

Commentary. Those who have played Dungeons and Dragons in its more recent incarnations may notice that the numbers on the rating tables are different: higher damage output at a given rating, but lower accuracy. This is intentional, as it is much harder to get flat bonuses to AC without spending resources. The target accuracy is 65% against a normal foe (neither defense focused nor glass cannon). That corresponds to a normal AC at level 20 of 16, which is where a mage-armored arcanist with maximum Dexterity would end up (at the weaker end), or below a plate-armored armsman (without a shield). It’s totally normal for a character to have ACs ranging from 15-20 at least before they use resources. However, baseline D&D had soft monsters, especially as defensive measures ramped up in later play. Which meant it required higher CRs to threaten people. Which caused undesirable results. The intent here is that combat should pose a threat even if the OR < level, as long as there are multiple monsters in play. Being forced to use your active defensive tools to absorb, avoid, or redirect incoming damage is totally normal and expected. You should not passively be able to ignore enemies whose OR is greater than half your level. And even ones below that can pose a threat in sufficient numbers.

Modifiers to Offensive Rating.

The following are some considerations for adjusting offensive rating. These are not intended to be exhaustive, nor are they intended to be rules. As with everything homebrew, play-testing with the actual party involved is the final determiner.

1. If the monster has an easy source of advantage on attacks such as Pack Tactics (advantage if an ally is within 5 feet of the target), increase their offensive rating by 1 after adjusting for accuracy.
2. If the monster has a significant ability (especially one that deals substantial damage like a breath weapon or one that would automatically take out an opponent on a failed save such as a banshee’s wail) that requires a saving throw your party is particularly weak at (such as a party with no one proficient in INT saves facing a mkhulu), increase the offensive rating by two.
3. If the monster has a damage transfer ability, increase the actual damage by 50% before calculating the offensive rating.
4. Summoning abilities depend on the mechanics—if the monster is expected to start combat with its allies summoned or the allies do not disappear when the monster is defeated, treat them as separate combatants. If they require in-combat actions to summon or control and/or disappear when the summoner is defeated, calculate their best rounds including those actions, using the monsters’ damage values if better than the casters’ values.

Calculating Defensive Rating

Defensive rating is based on the idea that a monster of Defensive Rating X should live for approximately 3 rounds against a baseline party of level X characters actively fighting it. This allows it the substantial chance of getting off its Big Cool Abilities at least once before being soundly defeated (the assumption is, after all, that the heroes win way more fights than they lose). As such, the primary factor in Defensive Rating is hit points. The underlying assumption is that monsters will generally be focus-fired, or at least need to survive being focus-fired by the entire party for some time.

Expected PC Damage and accuracy Not every action taken by player characters will be aimed at dealing damage. As a result, the system does not expect everyone to be fully-focused and optimized for damage dealing. Monsters are developed, and the defensive rating chart is built around the following principles:

• Player characters will generally hit between 60 and 70% of the time (including critical hits). Deviations from this are very noticeable on the player side. Very few options other than advantage and disadvantage exist to modify attack rolls; this is on purpose. Monsters who have AC more than 1 away from the expected value from the charts should have clear narrative signals that they are either really easy or really hard to hit. For example, a knight wearing plate armor and wielding a shield signals that they’re going to be a hard target, while an ooze with limited mobility is a signal of an easy-to-damage monster.

• Player characters will generally land between 50 and 80% of the saving throw-based abilities they use. This one has much broader range because there are 6 ability scores. Generally, few monsters have really poor WIS saves, while DEX tends to be one of the lower saves. CON tends to be the hands-down best saving throw. The others are mixed: STR tends to be ok to great, INT is all over the place, and CHA is high for fiends and dragons but generally poor otherwise.

• After accounting for accuracy, a not-very-optimized party is expected to deal on average 3x the damage of a similar-level rogue with a shortbow who gets sneak attack each round and hits (including critical hits) 70% of the time. This rogue-based reference point is referred to as Rogue Equivalent Damage (RED). The variance in party damage is expected to be roughly between 2.5 RED and  4-6 RED, depending on resource usage, targets, etc. This results in monsters generally surviving around 3 rounds, except at level 1 where a DR 1 monster survives roughly 2 rounds. Note that a damage-focused character normally does a baseline of ≈ 1.2-1.5 RED (with spikes up to 2+ RED when burning resources) and a spell-caster using cantrips ends up around ≈ 0.5 RED.

• Note from the table that there’s an uptick in expected lifetime against a baseline party around defensive rating 12. That’s because these monsters tend to be closer to boss monsters than normal scum. The expectation is that most significant encounters at high levels may have one boss monster and a bunch of smaller minions OR a larger swarm of smaller minions. A purely minion swarm at level 20 might look like 4-6 DR 10-11 monsters or 8-10 DR 6-8 monsters, while a boss encounter might be a single DR 17-20 and a 3-5 DR 6 or so monsters. Bounded accuracy ensures that these lower-DR monsters will still be a challenge.

To calculate Defensive Rating, follow the steps below:

1. calculate the base hit points of the monster, or pick an appropriate number from the Defensive Rating table table for the rating you approximately wish to end up with.
2. Adjust the base hit points for regeneration and substantial defensive measures (such as damage transfer abilities) based on the considerations below. This produces the effective hit points of the monster.
3. Compare the monster’s AC to that on the line that matches the effective hit point total. If the listed AC is 2 or more points higher than the monster’s AC, either change the AC or adjust the defensive CR down by one step for every 2 points difference. Similarly, if the monster’s AC is two or more points higher than the table value, you can adjust the monster’s AC to fit the table or adjust the defensive CR up by one step for every 2 points of difference.
4. Play test. This is especially important if the monster has special abilities whose effect on their longevity is situational or isn’t immediately apparent.

Once you’ve settled on a final hit point total, you can back-calculate the number of hit dice if you want, as long as you’ve defined the monster’s ability scores. Generally, larger creatures have larger hit dice (but fewer of them), with Tiny creatures having d4 HD by default and Gargantuan creatures having d20 HD. The number of HD is given by $\text{HD}=\frac{\text{hitpoint total}}{\text{HD average}+\text{Constitution modifier}}$, where the HD average is half of the maximum value on the die, plus 0.5 (e.g. a d4 has an average of 2.5). This will usually not come out cleanly—adjust the HP and HD until you’re happy. As long as the total doesn’t change to a different DR band, no other changes result.

Saving throw bonuses generally does not play into Defensive Rating much unless it has high saving throw modifiers in multiple of Constitution, Dexterity, and Wisdom. In that case, adjust defensive CR up by one if your party substantially relies on saving-throw based effects.