D&D combat in one page

D&D combat in one page (of really small type)

Initiative

Every round, each person acts once, from highest initiative to lowest. Your initiative is determined by rolling 1d20 + your Dex bonus, and stays the same until the end of the combat.

If some participants are taken by surprise, the other ones get a free round before the surprised ones can act.

Before the very first time you act in a combat, you are "flat-footed"; you don't get a Dex bonus to your armor class and can't make Attacks of Opportunity (see below).

Taking actions

There's lots of confusing stuff in the rules about standard actions, full-round actions, move actions, free actions, etc. Here's what I think is a simpler way to think about it:

You have 5 action points in a round to spend however you like.
Full-round actions cost 5 points.
Standard actions cost 3 points.
Move actions cost 2 points.
Free actions cost 0 points.
If you haven't otherwise moved, you can always move five feet for 0 points.

So you can take one full-round action, or a standard and a move, or two moves, and all of that is along with as many free actions as you like, plus maybe a move of five feet.

Attacks of Opportunity (AoO)

Some things that you do (typically, actions that distract you from defending yourself) provoke an Attack of Opportunity (AoO), which means that nearby opponents get a free attack (although a combatant can only take one AoO per round, even if multiple opponents provoke one). So try to avoid that. Withdraw and Move Five Feet are particularly helpful in avoiding attacks of opportunity while remaining mobile.

Actions

I've left out actions that are obscure or high-level. Actions that provoke 'Attacks of Opportunity' are marked with a star.

Withdraw (5). Move up to double your speed without provoking an AoO due to moving out of your current spot.
Run* (5). Move up to four times your speed, but lose your Dexterity bonus to your armor class.
Melee attack (3). Take one swing at an enemy. If you like, you can fight defensively by taking a -4 penalty to hit in return for a +2 armor class bonus.
Ranged attack* (3). -4 to hit if your target is engaged in melee with an ally of yours.
Unarmed attack* (3). Only your opponent gets an AoO.
Full attack (5). If you have multiple attacks, you need to use this action in order to use all of them.
Cast Spell* (3). If you take damage from the AoO, you have to make a Concentration check to finish the spell. You can try to avoid provoking an AoO by making a Concentration check (DC 15 + spell level), but if that fails, you lose the spell.
Move* (2) up to your speed. Causes an AoO if you move out of a threatened area.
Crawl* (2) five feet if you're unfortunate enough to be prone.
Draw a weapon (2)
Manipulate an item (2), like open a door or pick something up.
Stand up (2)
Drop an item (0)
Drop prone (0)
Talk (0)
Move five feet (0) but only if you are not otherwise moving this round.
Delay action (5). Wait until later this round to act, but your initiative stays at that reduced value.
Ready action (3). Prepare a specific action to respond to another specfic future action (e.g., "as soon as something comes through the door I shoot it").

Resolving a normal attack

Roll a d20 + your Base Attack Bonus + your Str modifier (or Dex if it's a missile weapon). If you beat your target's armor class (AC), you do damage equal to your weapon + your Str modifier (only if it's not a missile weapon).

If you roll a 1, you automatically miss. If you roll a 20, you automatically hit. If you roll in your weapon's threat range (typically just 20 but sometimes more), you may have a critical hit; roll again, and if that's a hit, you do some multiple of your usual damage.

For damage, roll the dice associated with your weapon and add your strength bonus (one and a half times the strength bonus if it's a two-handed weapon, or half of the strength bonus if the weapon is in your off hand). Damage can't go below 1.

Injury and death

A combatant reduced to 0 hit points is disabled (3 action points per turn). At -1 HP, you're dying. Every round, you have a 10% of becoming stable; otherwise you lose another hit point. When you reach -10, you die. You can stabilize someone by successfully making a DC 15 Heal check.

Combat modifiers

If the defender is behind physical cover, he gets +4 to his armor class.

If he has concealment (e.g., in darkness, fog, or tall grass), then any successful hit on him has a 20% chance of missing anyway.

If you and an ally are on opposite sides of a defender, he is flanked and you both get +2 to hit.

Special attacks

You can make other kinds of attacks than just swinging or shooting at someone, if you're feeling creative:

Aid another (3). Instead of attacking an enemy, roll against AC 10. If successful, your friend gets +2 to hit or +2 AC against that enemy until your next turn.
Bull rush* (3). Make an opposed Strength check to push the defender back five feet (useful if you're on the edge of a ravine!).
Charge (5). Move at least 10 feet and at most double your speed, then attack with +2 to hit and -2 to your AC.
Disarm* (3).
1. Your target gets an AoO. If he does damage, you fail.
2. Make an opposed attack roll. Two-handed weapons get +4, light weapons get -4. Larger combatants get +4 per size difference.
3. If you won, the defender is disarmed. If you failed, the defender gets to make a check as in 2. to disarm you.
Feint (3). Make a Bluff check against the opponent's Sense Motive + BAB. If you win, on your next attack against him he doesn't get a Dexterity bonus.
Grapple* (3).
1. Your target gets an AoO. If he does damage, you fail.
2. Make a melee touch attack to grab.
3. Make an opposed grapple check (BAB + Strength bonus + 4 per size difference) to hold and do unarmed strike damage.
On future rounds you can try to do more stuff or he can try to break the hold.
Overrun* (3).
1. Defender can simply step aside and let you move through if he wants.
2. If he blocks, make a Str vs Dex/Str check, plus 4 per size difference.
3. If you win, he is knocked prone and you can keep moving. If you lose, he makes the same check as in 2. to knock you prone.
Sunder* (3): try to attack his weapon or shield. Make an opposed attack roll as per Disarm to do damage to it.
Trip* (3).
1. Your target gets an AoO unless you are tripping it with a special trip-enabled weapon.
2. Make an unarmed touch attack (or a melee attack if you are using a weapon).
3. If that succeeds, make an opposed check as per Overrun.
4. If you win, he is knocked prone. If you lose, he makes the same check as in 3. to knock you prone.
Two-weapon attack (3). If you want to attack with two weapons, the first one is -6 to hit and the second is -10 (-4/-8 if the off-hand weapon is light, -4/-4 if you have the Two-Weapon Fighting feat, -2/-2 if both).