这个问题也许是值得探讨一下，因为判AOE清不了镜影的DM貌似不在少数。
Main FAQ 03-23-2007 p68
Q: Are the multiple figments from a mirror image spell legal targets for cleaving? That is, if you have the Cleave feat and you hit an image and destroy it, can you then attack another target within reach (such as another figment from the spell or perhaps the spell user)? What about Whirlwind Attack? Can you use this feat to attack all the images around the spell user? What about spells that allow multiple targets, such as magic missile? Can you aim magic missiles at different images?
A: For all intents and purposes, the figments from a foe's mirror image spell are your foes. You aim your spells and your attacks at the figments just as though they were real creatures. Any spell you can aim at a creature you can aim at an image. When you use a spell that allows you to select multiple creatures as targets, such as magic missile, you can choose multiple images as targets.
If you have the Cleave or Great Cleave feat, destroying an image with a melee attack triggers the feat (and your cleaving attack might well strike the spell user instead of another image). Likewise, you can use Whirlwind Attack to strike at any image you can reach. A Whirlwind Attack almost certainly will allow you to strike once at the spell user.
我把红字部分理解成——所有镜影，无论从哪方面看，都是和真身同等的敌人（只不过都挤在同一格罢了）。这样理解之后，就很容易解释Cleave和Whirwind Attack，以及multiple-target spells都对镜影有效。
诚然，火球是AOE，不属于上面提到的任何一种。但是按照上面的理解，我找不到火球打不了镜影的理由……
