D&D 5e Combat Rules Explained Simply

You walk into a room. The goblin looks at you. You look at the goblin. There's a long, uncomfortable pause, like running into your ex at the grocery store. Then the goblin pulls out a scimitar.

It's combat time.

D&D combat can seem intimidating from the outside. There are initiative rolls, action economies, opportunity attacks, conditions, concentration checks, and death saves. The Player's Handbook dedicates an entire chapter to it, and that chapter has subsections with their own subsections.

But here's a secret: the core system is actually pretty simple. It's just a series of turns where you decide what to do, roll some dice, and see what happens. Everything else is details on top of that basic framework.

This guide will walk you through every major combat mechanic in 5e, starting from zero. If you've never played D&D before, you'll understand combat by the end. If you've played a few sessions and still feel confused when your DM says "roll for initiative," this will clear things up.

Let's fight some goblins.

Step 1: Initiative (Who Goes First?)

When combat starts, the first thing that happens is everyone rolls initiative. This determines the turn order for the entire fight.

How to Roll Initiative

1. Every participant (players and enemies) rolls a d20 (that's the 20-sided die).
2. Add your Dexterity modifier to the roll. If your Dex is 14, your modifier is +2, so you add 2 to whatever you rolled.
3. The DM ranks everyone from highest to lowest. This is the initiative order.
4. That order stays the same for the entire combat, unless something specifically changes it (which is rare).

Example

You (Dexterity 14, modifier +2) roll a 15. Total: 17. The goblin (Dexterity 14, modifier +2) rolls an 11. Total: 13. Your friend the Cleric (Dexterity 8, modifier -1) rolls a 9. Total: 8.

Turn order: You, then the goblin, then the Cleric. The Cleric is going to die first and everyone knows it, but that's what healing spells are for.

Ties

If two participants tie, the one with the higher Dexterity score goes first. If they also have the same Dexterity score, the DM decides (or you flip a coin, or you arm wrestle, whatever works).

For more on initiative and how different features interact with turn order, check out our initiative and turn order guide.

Step 2: Your Turn (What Can You Actually Do?)

This is where the "action economy" comes in. On your turn, you get a specific set of things you can do. Understanding this is probably the single most important part of combat.

On Your Turn, You Get:

• One Action (the main thing you do)
• One Bonus Action (a quick, secondary thing, if you have one available)
• Movement (up to your speed, usually 30 feet)
• One Free Object Interaction (something trivial, like drawing your sword or opening a door)

That's it. One action, maybe one bonus action, some movement, and one small freebie. Here's what each one means.

Actions: The Main Event

Your action is the big thing you do on your turn. Here are the most common actions in combat:

Attack: You try to hit something with a weapon or spell. This is the most common action by far. Roll a d20, add your attack modifier, and compare it to the target's Armor Class (AC). If your total equals or exceeds their AC, you hit. Then you roll damage.

Cast a Spell: Many spells use your action to cast. Fireball, Healing Word, Shield of Faith. If a spell says "1 action" in its casting time, this is what it means.

Dash: You give up your action to move extra. Instead of doing something cool, you run. Your movement for the turn doubles. Sometimes running away is the smart play.

Dodge: You focus entirely on defense. Until your next turn, attack rolls against you have disadvantage (roll two d20s and take the lower), and you make Dexterity saving throws with advantage (roll two d20s and take the higher). Good when you're surrounded and need to survive.

Disengage: You can move without provoking opportunity attacks for the rest of the turn. (We'll cover opportunity attacks later. They're the "gotcha" mechanic that catches every new player off guard. Literally.)

Help: You assist an ally. The next attack roll they make against a target within 5 feet of you gets advantage. Teamwork!

Hide: You attempt to hide in combat. Make a Dexterity (Stealth) check. If you succeed, you're hidden, which gives you advantage on your next attack roll and makes it harder for enemies to target you.

Ready: You prepare an action to trigger when something specific happens. "I ready my attack for when the goblin comes through the door." When the trigger occurs, you use your reaction to do the thing. This is tactically powerful and underused.

Use an Object: You interact with something more complex than drawing a weapon, like drinking a potion, throwing a flask of oil, or pulling a lever.

Bonus Actions: The Side Dish

Not everyone has a bonus action available every turn. You only get to use a bonus action if you have a feature or spell that specifically says "bonus action." Some examples:

• Rogues can use Cunning Action as a bonus action to Dash, Disengage, or Hide.
• Two-weapon fighting lets you make an off-hand attack as a bonus action.
• Some spells (like Healing Word or Misty Step) have a casting time of "1 bonus action."
• Monks can use several ki features as bonus actions.

If you don't have anything that uses a bonus action, you don't get a bonus action that turn. You can't just use it as a second action. It's not a "mini action." It's a specific resource that only activates when something tells it to.

This is one of the most commonly misunderstood rules in all of 5e. For a complete breakdown of how actions, bonus actions, and reactions interact, see our action economy guide.

Movement: Getting Around

On your turn, you can move up to your speed (usually 30 feet). Some important details:

• You can split your movement around your action. Move 15 feet, attack, then move 15 more feet. Totally legal.
• Difficult terrain costs double movement. Moving through rubble, thick forest, or a room full of caltrops means every foot costs 2 feet of movement.
• Standing up from prone costs half your movement speed.
• You can move through an ally's space, but you can't stop there (unless they're a different size). You can't move through an enemy's space at all (unless they're two sizes bigger or smaller than you).

Free Object Interaction: The Freebie

Once per turn, you can interact with one object for free. Draw a sword. Open a door. Pick up a dropped weapon. Kick a pebble at the goblin's face (for flavor, not damage).

If you want to interact with a second object, you need to use your action. So you can draw your sword for free, but if you also want to pull out a potion, that costs your action.

Step 3: Making an Attack

Attacking is the bread and butter of combat. Here's exactly how it works.

Melee Attacks (Swords, Axes, Fists)

1. Roll a d20.
2. Add your attack modifier. For melee weapons, this's usually your Strength modifier + your proficiency bonus. If you're a level 1 Fighter with 16 Strength (+3 modifier) and a +2 proficiency bonus, you add +5.
3. Compare to the target's AC. If your total meets or exceeds their Armor Class, you hit.
4. Roll damage. Each weapon has a damage die. A longsword is 1d8. A greataxe is 1d12. Add your Strength modifier to the damage roll (but not your proficiency bonus, that's only for the attack roll).

Ranged Attacks (Bows, Crossbows, Thrown Weapons)

Same process, but you use your Dexterity modifier instead of Strength (for most ranged weapons). Also:

• Long range: If the target is beyond the weapon's normal range but within its long range, you attack with disadvantage.
• Close quarters: If an enemy is within 5 feet of you, you have disadvantage on ranged attacks. The goblin is in your face and you're trying to snipe someone 60 feet away? Yeah, that's hard.

Spell Attacks

Some spells require attack rolls (like Fire Bolt, Eldritch Blast, or Guiding Bolt). These use your spellcasting ability modifier + proficiency bonus. Same "meet or beat the AC" rule.

Critical Hits and Misses

• Natural 20: If the d20 shows a 20 (before modifiers), it's a critical hit. You hit regardless of AC, and you roll the damage dice twice. A longsword crit does 2d8 + Strength modifier.
• Natural 1: If the d20 shows a 1, it's an automatic miss. Regardless of modifiers. Yes, even if you have +15 to hit and the goblin has an AC of 7. The dice have spoken.

Advantage and Disadvantage

This is 5e's elegance at its finest. Instead of tracking a dozen situational modifiers (+2 for flanking, -1 for fog, +1 for high ground), 5e uses a binary system:

• Advantage: Roll two d20s and take the higher result.
• Disadvantage: Roll two d20s and take the lower result.

If you have both advantage and disadvantage on the same roll, they cancel out and you roll normally. This is true regardless of how many sources of each you have. Three advantages and one disadvantage? They all cancel. You roll one d20.

Common sources of advantage: attacking a prone target from melee range, attacking while hidden, attacking a target that's been affected by Faerie Fire.

Common sources of disadvantage: attacking a prone target from range, attacking while poisoned, attacking a dodging target.

Step 4: Damage, Hit Points, and Going Down

When you hit something, you deal damage. When something hits you, you take damage. Your hit points (HP) are the buffer between "alive and fighting" and "bleeding out on the floor."

How Damage Works

1. Roll the damage die (or dice) specified by the weapon or spell.
2. Add the relevant modifier (Strength for melee, Dexterity for finesse/ranged, spellcasting ability for some spells).
3. The target subtracts that number from their hit points.

Damage Types

D&D has 13 damage types: slashing, piercing, bludgeoning, fire, cold, lightning, thunder, poison, acid, necrotic, radiant, psychic, and force. Damage types matter because some creatures are resistant (take half damage), immune (take no damage), or vulnerable (take double damage) to specific types.

Hitting a skeleton with a club (bludgeoning)? Extra effective, since they're vulnerable. Trying to poison an undead? Won't work. They're immune. This isn't just flavor. It changes how fights play out.

Dropping to 0 HP

When a creature (player or monster) drops to 0 hit points, they fall unconscious and start making death saving throws. They don't die immediately (usually). More on this in the Death Saves section below.

Monsters typically just die at 0 HP. The DM doesn't usually bother with death saves for the goblin you just clobbered. It's dead. Move on.

Step 5: Conditions

Conditions are status effects that alter what a creature can do. They're one of the most strategically important parts of 5e combat, and they're also the rules that get forgotten most often.

Here are the conditions you'll encounter most frequently:

Blinded

Can't see. Attacks against you have advantage. Your attacks have disadvantage. Anything that relies on sight (like many spells) automatically fails.

Charmed

You can't attack the charmer or target them with harmful abilities. The charmer has advantage on social checks against you. You're basically their biggest fan for the duration.

Frightened

You have disadvantage on ability checks and attack rolls while you can see the source of your fear. You can't willingly move closer to it. Your Barbarian is very brave until the dragon shows up, and then suddenly there's something very interesting happening in the opposite direction.

Grappled

Your speed becomes 0. That's it. You can still attack, cast spells, and do everything else normally, you just can't move. To escape, you use your action to make a Strength (Athletics) or Dexterity (Acrobatics) check contested by the grappler's Athletics.

Incapacitated

You can't take actions or reactions. That's the whole condition. It's bad because it often shows up as part of other conditions (Stunned, Paralyzed, Unconscious all include Incapacitated).

Paralyzed

Incapacitated, can't move, can't speak. Auto-fail Strength and Dexterity saves. Attacks against you have advantage, and any hit from within 5 feet is an automatic critical. This is one of the worst conditions in the game. If you get paralyzed in melee range of three enemies, start thinking about your next character.

Poisoned

Disadvantage on attack rolls and ability checks. Sounds mild. It's not. Disadvantage on every attack for potentially several rounds is brutal, especially for martial classes who rely on landing hits.

Prone

Attacks against you from melee have advantage. Attacks against you from range have disadvantage. Your attacks have disadvantage. Standing up costs half your movement. Enemies love knocking you prone.

Restrained

Speed is 0, attacks against you have advantage, your attacks have disadvantage, disadvantage on Dexterity saves. Like grappled but worse.

Stunned

Incapacitated, can't move, auto-fail Strength and Dexterity saves, attacks against you have advantage. Essentially paralyzed without the auto-crit, which is still devastating.

Unconscious

Everything from incapacitated and stunned, plus you drop what you're holding, fall prone, auto-fail Strength and Dexterity saves, attacks have advantage, and hits from within 5 feet are auto-crits. This is what happens at 0 HP.

Step 6: Reactions and Opportunity Attacks

A reaction is a special response triggered by something happening outside your turn. You get one reaction per round (it refreshes at the start of your next turn).

Opportunity Attacks

The most common reaction. When a creature you can see moves out of your melee reach, you can use your reaction to make one melee attack against them. This is why the Disengage action exists.

The classic new-player mistake: Your Wizard is next to a goblin. On the Wizard's turn, they move away to get some distance and cast a spell. The goblin gets an opportunity attack and hits them. The Wizard takes damage. The Wizard's player looks confused and slightly betrayed.

If you want to move away from an enemy without getting smacked, use the Disengage action (or be a Rogue and use Cunning Action for a bonus action Disengage, because Rogues get all the nice things).

Other Common Reactions

• Shield (spell): +5 AC until your next turn. The Wizard's best friend.
• Counterspell: Negate an enemy's spell. The BBEG tries to cast Fireball, and your Wizard says "no." Extremely satisfying.
• Uncanny Dodge (Rogue): Halve the damage from an attack that hits you. Rogues really do get all the nice things.

Step 7: Death Saving Throws

Your character drops to 0 HP. They're unconscious, bleeding out, and the dramatic music kicks in. Now what?

How Death Saves Work

At the start of each of your turns while at 0 HP, you roll a d20. No modifiers (usually).

• 10 or higher: That's a success.
• 9 or lower: That's a failure.
• Three successes: You stabilize at 0 HP. You're unconscious but no longer dying.
• Three failures: You die. For real. Roll a new character.
• Natural 20: You regain 1 HP and wake up. Dramatic comeback! The table goes wild.
• Natural 1: Counts as two failures. The table gasps.

Important Details

• Successes and failures don't need to be consecutive. Three total of either ends the process.
• If you take damage while at 0 HP, that's an automatic failure. If the damage comes from a critical hit (any melee attack within 5 feet auto-crits on unconscious targets), it counts as two failures.
• If you take massive damage (enough to reduce you to negative HP equal to your max HP), you die instantly. No death saves. This is rare but very possible at low levels.
• Any healing, even 1 HP, immediately stabilizes you and ends the death save process. This is why Healing Word is the best low-level spell in the game.

For a detailed breakdown of death save strategy and math, check out our death saves guide.

Step 8: Concentration

If you're a spellcaster, this is critical. Many powerful spells require concentration. You can only concentrate on one spell at a time, and if your concentration breaks, the spell ends.

What Breaks Concentration

• Taking damage. When you take damage while concentrating, you make a Constitution saving throw. The DC is either 10 or half the damage taken, whichever is higher. If you fail, the spell ends.
• Casting another concentration spell. The moment you start concentrating on a new spell, the old one drops. No exceptions.
• Being incapacitated or killed. Unconscious, stunned, or dead? Concentration gone.

Why This Matters

Many of the best spells in the game are concentration. Bless, Haste, Spirit Guardians, Wall of Force, Hypnotic Pattern. If you cast Haste on your Fighter and then lose concentration, the Fighter loses an entire turn (Haste's penalty for ending early). Protecting your concentration is a core tactical skill.

For everything you need to know about concentration mechanics, see our concentration rules guide.

Step 9: Cover and Environment

The battlefield isn't just a flat grid. Cover matters.

• Half cover (+2 AC and Dex saves): A low wall, furniture, another creature. Anything that blocks about half your body.
• Three-quarters cover (+5 AC and Dex saves): An arrow slit, a thick tree trunk. Most of your body is hidden.
• Total cover: Completely hidden. Can't be directly targeted by attacks or spells that require line of sight.

Smart positioning wins fights. Standing behind a pillar for +5 AC is sometimes better than anything on your character sheet.

Putting It All Together: A Sample Round

Time for an example. One complete round of combat.

Setup: You're a level 3 Fighter with a longsword and shield (AC 18, HP 28). You're fighting two goblins (AC 15, HP 7 each). The Cleric (AC 16, HP 22) is behind you.

Initiative: You rolled 17, Goblin A rolled 14, Goblin B rolled 12, Cleric rolled 8.

Your turn: You move 15 feet toward Goblin A and use the Attack action. You roll a d20 and get 14, plus your +5 modifier makes 19. That beats AC 15, so you hit. You roll 1d8 for your longsword and get 6, plus 3 for your Strength modifier is 9 damage. Goblin A had 7 HP. It's dead. You still have 15 feet of movement, so you move toward Goblin B.

Goblin A's turn: It's dead. Skip.

Goblin B's turn: It attacks you. Rolls a 16 plus its +4 modifier is 20. That beats your AC of 18. It deals 5 damage. You're at 23 HP. Annoying, but manageable.

Cleric's turn: Casts Sacred Flame on Goblin B. The goblin makes a Dexterity save and fails. Takes 1d8 radiant damage: 7. The goblin had 7 HP. It's dead.

Combat over. Total elapsed time at the table: about 3 minutes. In the fiction: about 6 seconds.

How The Endlessness Handles All of This

We'll keep the marketing brief and direct: The Endlessness tracks all of these rules automatically. Initiative, turn order, action economy, conditions, concentration, death saves, all of it. The AI doesn't approximate combat or narrate around the rules. It runs the actual system.

When your character is grappled, your speed is 0 until you break free. When you fail a concentration check, the spell drops. When you roll a natural 1 on a death save, it counts as two failures.

You focus on the fun part (deciding what to do). The system handles the bookkeeping.

Common Combat Mistakes to Avoid

1. Forgetting concentration checks after taking damage. Your DM should remind you, but track it yourself too.
2. Moving away from enemies without Disengaging. That opportunity attack will hurt.
3. Using a bonus action spell and a regular spell in the same turn. If you cast a spell as a bonus action, the only other spell you can cast that turn is a cantrip with a casting time of one action. No Healing Word + Fireball combos.
4. Not using your reaction. Opportunity attacks, Shield, Counterspell. If you're ending rounds with your reaction unspent, you're leaving value on the table.
5. Ignoring cover. That +2 or +5 to AC is free. Use it.
6. Burning all your resources in the first fight. D&D is balanced around 6-8 encounters per adventuring day. If you blow every spell slot in the first fight, you'll be throwing cantrips at the dragon later.

Quick Reference Card

Save this for your next session:

Your turn: Action + Bonus Action (if available) + Movement (up to speed) + Free Object Interaction

Attack roll: d20 + ability modifier + proficiency bonus vs. AC

Damage roll: weapon/spell die + ability modifier

Death saves: d20 at start of turn. 10+ = success. 9- = failure. 3 of either ends it.

Concentration: Con save on damage. DC = 10 or half damage, whichever is higher.

Opportunity attack: Reaction when enemy leaves your reach.

Go roll some dice. Those goblins aren't going to fight themselves.