My group and I are playing D&D 3.5e, and we're unclear on what the ruling is: can Polymorph Any Object affect an abomination?
SRD: Polymorph Any Object
Abominations are creatures, but as a creature type they do possess an immunity to polymorph, so they would not be a valid target.
Are you talking about abominations (the ill-starred yet frighteningly powerful offspring of deities and non-humanoids, like atropals and anaxims) or aberrations (alien entities with origins beyond mortal comprehension, like aboleths and illithids)?
Aberrations do not have any special immunity to polymorphing. Or at least, they aren't immune just because they're aberrations: individual creatures may have immunity from other sources. I'd rule that aberrations form their own "kingdom" for purposes of polymorph spells, which would mean that polymorphing an aberration to anything that is not an aberration (or the reverse) would face some serious time constraints, but that's just my interpretation, and it's still not the same thing as immunity.
Abominations, on the other hand, are immune to polymorph effects. I'd say that this includes POA.