Baleful Polymorph

[LetterOfTheLaw]

I cast Baleful Polymorph on a hostile skeleton, and it seemed to gain quite a few extra hitpoints. At CL12 a lesser missile storm and 2x magic missile didn't make a dent in its hp bar, but the log noted that it caused damage. A few scorching rays quickly dispatched it afterwards.

Not sure what's going on or if stumbled into an unknown necromancy ritual... Polymorph form in question was bat.