Several illusory duplicates of the character pop into being, making it difficult for enemies to know which target to attack. The figments stay near the character and disappear when struck.

Mirror image creates 1d4 images plus one image per three caster levels (maximum eight images). These figments separate from the character and remain in a cluster, each within 5 feet of at least one other figment or the character. The character can move into and through a mirror image. When the character and the mirror image separate, observers can’t use vision or hearing to tell which one is the character and which the image. The figments may also move through each other. The figments mimic the character's actions, pretending to cast spells when the character casts a spell, drink potions when the character drinks a potion, levitate when the character levitates, and so on.

Enemies attempting to attack the character or cast spells at the character must select from among indistinguishable targets. Generally, roll randomly to see whether the selected target is real or a figment. Any successful attack roll against a figment destroys it. A figment’s AC is 10 + size modifier + Dexterity modifier. Figments seem to react normally to area spells (such as looking like they’re burned or dead after being struck by a fireball).

While moving, the character can merge with and split off from figments so that enemies who have learned which image is real are again confounded.

An attacker must be able to see the images to be fooled. If the character is invisible or an attacker shuts her eyes, the spell has no effect, though being unable to see carries the same penalties as being blinded: In addition to the obvious effects, a blinded creature suffers a 50% miss chance in combat (all opponents have full concealment), loses any Dexterity bonus to AC, grants a +2 bonus to attackers’ attack rolls (they are effectively invisible), moves at half speed, and suffers a –4 penalty on most Strength- and Dexterity-based skills.