From Guild Wars Wiki
- They wander back and forth, either in a small area or over a patrol range.
- If you get within the danger zone, they become aggressive and attack you.
- When fighting, they have two priorities of who to target: weakest foes (by health and armor rating) and closest foes.
- They each have a set of skills to which they are limited. The way they use these skills is embedded into the skill itself, so monsters with the same skills use them the same way.
Monsters with non-standard AI
There are some specifically-coded exceptions.
- Some Monk and Ritualist monsters may kite attackers.
- Some monsters (such as Siege Wurms) are completely stationary, but some are only stationary under certain situations:
- Many "sprout" Plants are typically stationary, but they sometimes move, particularly when taking area damage over time. This is also true of Brooding Thorns and some Scarab Nest Builders.
- Burrowing Wurms are stationary while out of the ground, but they move while burrowing. They burrow after being out of the ground for a while, and will also burrow if no targets are within range.
- Special boss-like foes (such as Glint, Kuunavang, Shiro Tagachi, and the Undead Lich) have special AI that determines unique skill usage or movement patterns.
- AI will only cast skills that trigger on spell casting (such as Backfire) on targets wielding a spellcasting weapon, so characters with spells on their skill bar and wielding a martial weapon will cause AI to not cast Backfire on them.
- Some skills that inflict Blind are used differently in Normal mode and Hard mode:
- In Normal mode, AI will only use skills that inflict Blind (such as Blinding Flash and Throw Dirt) on a foe wielding a martial weapon. A spellcaster wielding a martial weapon (e.g. caster weapon) can cause AI to waste time to activate a Blind-inflicting skill on them (e.g. causing a ranger to stop attacking and move into touch range to use Throw Dirt, which would relieve pressure on your party).
- In Hard mode, AI will only use some skills that inflict Blind (such as the aforementioned skills) on a martial primary profession foe wielding a martial weapon.
- AI will only use some skills that inflict Blind (such as Eruption) on a foe wielding a martial weapon, regardless of it being Normal or Hard mode.
- AI will use skills that have no other effect other than inflicting a condition (such as Blinding Powder, Hunter's Shot, and Sever Artery) on spirits, even though they are immune to all conditions except burning.