Rules of Combat
A typical combat encounter is a clash between two sides, a flurry of weapon swings, feints, parries, footwork, and spellcasting.
Combat in Dungeons & Dragons 5e is structured into rounds where each participant in the battle takes a turn. One round represents about 6 seconds in the game world, so although we act out turns one at a time, it is assumed they happen almost simultaneously in the game world.
At the start of a combat encounter, players roll a d20 + their Dexterity modifier. This is a representation of how quickly a character reacts to the dangerous scenario.
This is called rolling for initiative (turn order). The initiative remains the same for the entire combat.
On every turn, you can (in any order):
Perform an Action
Perform a Bonus Action (if applicable).
When it is not your turn, you may have the opportunity to use a Reaction.
Below, you'll find more details about what can be done on your turn as well as information about Damage and Healing.
A character’s movement speed is how many feet they can move on their turn. When using a grid map, 1 square represents 5ft. So, a character with a speed of 30ft can move 6 squares.
You can move in any direction, including diagonally.
You are not required to take your full movement, and you can move, take an action, and then move again if you have additional movement remaining.
Sometimes there are obstacles that hinder movement, like rubble, thick mud, or tangled roots. The term for this is difficult terrain.
A square with difficult terrain counts as 10ft of movement instead of 5ft.
Moving through another creature’s space always counts as difficult terrain. You can move through allies, but you are unable to pass through enemies unless they are much larger or smaller than you.
You can fall prone at no movement cost, but it takes half of your total movement to stand from being prone. You cannot stand if you don't have enough movement left or your speed is 0.
Crawling acts the same as difficult terrain.
Your action is the main thing you do on your turn. Most often, a character will use their action to attack or cast a spell. But there are a lot of different possibilities.
When a character describes an action not detailed here, the DM will decide whether that action is possible and what kind of roll you need to make, if any, to determine success or failure.
Various class features, spells, and other abilities let you take an additional action on your turn called a bonus action. You can only take one bonus action on your turn, so you must choose which bonus action to use when you have more than one available.
There are many class features that take 1 bonus action to use.
Some examples include: a barbarian's Rage, a bard's Inspiration, or a rogue's Cunning Action.
When you use the Attack action while wielding a light melee weapon (such as a handaxe or scimitar), you can use a bonus action to attack with a light melee weapon that you're holding in the other hand.
You don't add your ability modifier to the damage of the bonus attack, unless the modifier is negative.
If either weapon has the thrown property, you can throw the weapon instead of making a melee attack with it.
Cast a Spell
Some spells have a casting time of 1 Bonus Action.
If you cast a spell a spell as a bonus action, you can't cast another spell during the same turn except for a cantrip with a casting time of 1 action.
See the Magic and Spellcasting page for more details about spellcasting.
Part of the Ready Action. When the trigger for the readied action occurs, you use your reaction to perform it.
When an enemy leaves your melee range, you can use your reaction to take a free attack called an opportunity attack.
Cast a Spell
A small number of spells are so swift they have a casting time of 1 Reaction.
Probably the most commonly used reaction spell is the shield spell.
Damage and Healing
Injury and risk of death are constant companions of those who explore the worlds of D&D.
Hit Points: Hit Points (or HP) represent a combination of physical and mental durability, the will to live, and luck. Whenever a creature takes damage, that damage is subtracted from its hit points until it drops to 0 hit points.
Healing: Unless it results in death, damage isn't permanent, and even death is reversible with powerful magic. Rest can restore a creature's HP and magical methods can do so even faster. Healing can't cause a creature to exceed its hit point maximum.
Dropping to 0 HP: When you drop to 0 HP, you either die instantly or fall unconscious.
Instant Death: Massive damage can kill you instantly. When damage reduces you to 0 HP and there is damage remaining, you die if the remaining damage equals or exceeds your hit point maximum.
Falling Unconscious: if damage reduces you to 0 HP but fails to kill you, you fall unconscious and begin making death saving throws.
Death Saving Throws: Whenever you start your turn with 0 HP, you must make a death saving throw to determine whether you creep closer to death or hang onto life. Unlike other saving throws, this one isn't tied to any ability score. You roll a d20. If the roll is 10 or higher, you succeed. On your third success, you become stable. On your third failure, you die. The successes and failures do not need to be consecutive. Both reset when you regain any hit points or become stable.
Damage at 0 Hit Points: If you take any damage while you have 0 HP, you suffer a death saving throw failure. If the damage is from a critical hit, you suffer 2 failures.
Stabilizing a Creature: The best way to save a creature with 0 HP is to heal it. If healing is unavailable, another character can use an action to administer first aid. It requires a successful DC 10 Wisdom (Medicine) check.
A stable creature doesn't make death saving throws, but it does remain unconscious. If it is never healed, it will regain 1 HP after 1d4 hours.
Knocking a Creature Out: Sometimes an attacker wants to incapacitate a foe, rather than deal a killing blow. When an attacker reduces a creature to 0 HP with a melee attack, the attacker can knock the creature out. The attack can make this choice the instant the damage is dealt. The creature falls unconscious and is stable.