Attacks of opportunity

Version 0.31: This article is up to date for the latest stable release of Dungeon Crawl Stone Soup.

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. Even if you are faster than the opponent, attacks of opportunity can still be made.

The attack of opportunity and following movement happen in a single monster turn. However, for every attack of opportunity made, there a 50% chance for it to lose an extra 10% of a turn. Also, random energy does not apply whenever an attack of opportunity actually happens.

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.

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
  • Cannot move: Constricted, caught in a web/net
  • Cannot attack: Fleeing
• If you swap places with an ally, so that the ally blocks the monster's movement, you avoid an attack of opportunity.
• 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.

The following can help you escape from a melee monster, but attacks of opportunity can still occur:

• Being faster than the monster. For example, against a 100% speed monster, a hasted player can take at most 2 attacks of opportunity before escaping melee range.
• Confusing the monster. There's a ~41% chance for a confused monster to follow you, so it's 41% as likely for an attack of opportunity to be made.
• Becoming invisible or blinding the monster. Monsters have some memory of where you last where, so these statuses aren't reliable, but can cause a monster to stop chasing you.

Strategy

Watch out! When retreating, a 100% speed enemy with AOO gets more attacks than an adder without AOO. Always try to reposition (say, to a upstairs) before you get adjacent to them.

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

• Swapping places with a summon or other type of ally.
• Prevent the monster from moving: Throwing net, BVC.
• Translocating yourself away: Blink, Passage of Golubria, scroll of teleport, scroll of blinking.
• Sending the monster away: Iskenderun's Mystic Blast, Dispersal (spell and darts, scroll of butterflies, phial of floods.

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, if the monster is confused or blinded, or if you were invisible and the monster who couldn't see invisible.
  • 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.