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System Reference Document 5.2.1
Running a MonsteR
To ensure a monster acts in accordance with its 
Challenge Rating, follow these rules during combat:
Special Abilities. If the monster has a special abil-
ity that deals a lot of damage but has a limited 
number of uses, such as a recharging breath 
weapon or a spell it can cast only once per day, 
have it use that special ability as quickly and as 
often as possible.
Multiattack. If the monster has Multiattack, have 
it use Multiattack on any of its turns in which 
it’s not using one of its more powerful abilities.
Bonus Actions, Reactions, Legendary Actions. If 
the monster has Bonus Actions, Reactions, or 
Legendary Actions in its stat block, make sure it 
uses them as often as it can.
Hit Points
A monster’s Hit Points are presented as a number 
followed by parentheses, where the monster’s Hit 
Point Dice are provided, along with any contribu -
tion from its Constitution. Either use the number for 
the monster’s Hit Points or roll the die expression in 
parentheses to determine the monster’s Hit Points 
randomly; don’t use both.
 A monster’s size typically determines the die used 
to calculate its Hit Points, as shown in the Hit Dice 
by Size table.
Hit Dice by Size
Monster Size Hit Die Average HP per Die
Tiny d4 2½
Small d6 3½
Medium d8 4½
Large d10 5½
Huge d12 6½
Gargantuan d20 10½
A monster’s 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).
 For more on Hit Points, see “Playing the Game .”
Speed
The Speed entry specifies a monster’s Speed. Some 
monsters have one or more of the following speeds: 
Burrow, Climb, Fly, Swim. Rules for Speed and these 
specials speeds appear in “Rules Glossary .”
Ability Scores
Every monster has six ability scores along with 
corresponding ability score modifiers and saving 
throw modifiers. For more information on ability 
scores and saving throws, see “Playing the Game .”
Skills
The Skills entry specifies a monster’s skill profi -
ciencies, if any. For example, a monster that is very 
perceptive and stealthy might have bonuses to Wis -
dom (Perception) and Dexterity (Stealth) checks. A 
skill bonus is the sum of a monster’s relevant ability 
modifier and its Proficiency Bonus. Other modifiers 
might apply.
Resistances and Vulnerabilities
These entries list a monster’s Resistances and Vul -
nerabilities, if any. See “Playing the Game” for more 
information.
Immunities
This entry lists the monster’s Immunities, if any. If 
the monster has damage and condition Immunities, 
the damage types are listed before the conditions. 
See “Playing the Game” for details.
Gear
Monsters have proficiency with their equipment. If 
a monster has equipment that can be given away or 
retrieved, the items are listed in the Gear entry. The 
monster’s stat block might include special flour -
ishes that happen when the monster uses an item, 
and the stat block might ignore the rules in “Equip -
ment” for that item. When used by someone else, a 
retrievable item uses its “Equipment” rules, ignor -
ing any special flourishes in the stat block.
 The Gear entry doesn’t necessarily list all of a 
monster’s equipment. For example, a monster that 
wears clothes is assumed to be dressed appropri -
ately, and those clothes aren’t in this entry.
 Equipment mentioned outside the Gear entry is 
considered to be supernatural or highly specialized, 
and it is unusable when the monster is defeated.
Ammunition and Ranged Attacks
A monster that requires ammunition to make 
ranged attacks carries the necessary ammunition.
Equipping a Monster with Other Items
You may equip monsters with additional gear how -
ever you like, using the items in “Equipment” for 
inspiration. 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.
 Beware of giving a monster combat-oriented 
magic items, since those might alter the monster’s 
Challenge Rating. If you do give a monster a magic 
item, the monster can have Attunement with magic 
items as noted in “Equipment.” A monster with 