Attacks of opportunity

Version 0.31: This article may not be up to date for the latest stable release of Crawl.

When you move away from an enemy, they have a small (1/3) chance of taking advantage and launching a free attack. Repositioning and retreating is often still good, but keep an eye out for those extra attacks.

Attacks of opportunity (AOO, AOOp) can trigger whenever you move away from an enemy in melee.

Useful Info

Whenever you move away from an enemy's melee attack range, and the monster would pursue, it has a 33% chance to trigger an attack of opportunity. This allows it to move and attack simultaneously. They can only occur if a monster would choose to pursue. Enemies with reaching attacks can make attacks of opportunity from 2 tiles away.

The time spent to do both actions is a single monster turn, but with a 50% chance for it to lose an extra 10% of a turn. If a monster attacks slower than it moves, or moves slower than the attacks, it takes time equal to the slower of the two actions.

Note that random energy does not apply whenever an attack of opportunity happens. However, if a monster would be eligible for an attack, but doesn't actually get one, random energy will apply.

Avoiding

The following conditions will prevent attacks of opportunity entirely:

• If a monster would choose not to move or melee attack, it won't make attacks of opportunity. For example, a centaur will prefer to use its bow over a weak melee attack.
• Monsters who cannot move or melee attack will not perform attacks of opportunity, so the following statuses stop them entirely:
  • Incapacitation: Asleep, paralysed, petrified, or confused
  • Cannot move: Constricted, caught in a web/net
  • Cannot attack: Fleeing
• If an enemy cannot see you - that is, you are invisible to the attacker or the attacker is blinded, you avoid attacks of oppotunity.
• If you swap places with an ally, so that the ally blocks the monster's movement, you avoid that attack of opportunity. However, if the ally is killed during the turn when you switched, and another monster could step into its place and make an attack of opportunity, it may do so.
• Zin's Sanctuary prevents all attacks. This protection is retroactive - if you were previously outside the area and moved inside, the Sanctuary still protects you.
• You become immune to attacks of opportunity while performing martial attacks, rampaging, or Serpent's Lash.
• Translocations don't count as movement, so you can use them safely.

Being faster than the monster can help you escape from a melee monster, but attacks of opportunity can still occur. For example, against a 100% speed monster, a hasted player can take at most 2 attacks of opportunity before escaping melee range.

Strategy

Watch out! When retreating, a 100% speed enemy with AOO gets more attacks than an adder would without AOO. Always try to reposition (say, to a upstairs) before you get adjacent to them. Once you're adjacent to a melee enemy, you should only move if you have a good reason to.

Should you need to retreat from a bad fight, your options are limited. Common ways to escape include:

• Swapping places with a summon or another type of ally
• Prevent the monster from moving: Throwing net, Grave Claw, BVC, wand of roots
• Translocating yourself away: Translocations magic, scroll of teleport, scroll of blinking
• Sending the monster away: Iskenderun's Mystic Blast, Dispersal (spell and darts), scroll of butterflies, scroll of fear, phial of floods / Gell's gravitambourine
• Inflicting a status on the enemy (not as reliable): Hexes, Mephitic Cloud

History

• In 0.31, attacks of opportunity were reworked. Prior to this version:
  • Monsters didn't have a 50% chance to lose 0.1 of a turn after making an opportunity attack.
  • Monsters only made attacks of opportunity if you were adjacent, not in melee range. Therefore, monsters with reaching attacks couldn't make attacks of opportunity. Their AI would let you get 2 tiles away before chasing, thus invalidating opportunity attacks.
  • You were immune to attacks of opportunity if you moved faster than the monster.
  • Certain attack flavours, such as engulf, constrict, and any effect that moved the player or monster, were disabled during attacks of opportunity.

Also, random energy was re-introduced in this version.

• Attacks of opportunity were introduced in 0.29, as a replacement for energy randomisation.