Longbow said:
Yes, Displacement and Mirror Image stacks / works together. The images benefit from the concealment. Source: v.3.5 Main D&D FAQ, page 33.
http://www.wizards.com/default.asp?x=dnd/er/20030221a
kjenks said:
If you use the version of Mirror Image from the Main 3.5e FAQ (all images in one square), adding Displacement on top of Mirror Image doesn't help at all against a creature who simply closes his eyes and swings.
Yes, the 3.5 FAQ has weird decisions on Mirror Image.
They decided that all visual spell effects (i.e. game mechanics) and not just the visual aspects of spells combine with regard to Mirror Image.
So, if you have Mirror Images up, they blur and have a miss chance if you have Blur up.
If you have Displacement up, they displace and have a miss chance.
So although the target of a Blur or Displacement spell is a single creature and magic that only targets a creature should not target another spell, WotC ruled that creature targeting magic applies to his Mirror Image images as well.
Displacement is REALLY strange with regard to this since what it effectively does is make the caster invisible (i.e. light does not reflect from his true position, rather it travels through his true position just like invisibility) and places a visible image of him nearby.
Hence, Displacement and Mirror Images should cause the images to go invisible at their "true location" (just like the caster is effectively invisible), just like with normal invisibility. The caster's true location is invisible, hence, all of his images should be invisible. IMO.
I think WotC dropped the ball on this one.