If it is not a bug it sure seems like it should be.

I was in the Arena Quest.  I had Procipinee, Svedd, my Storm Dragon, and 4 archers (good ones).

The Obsidian Golems are immune to the Storm Dragons fire breath and tail sweep.  I think the fire breath is a stretch, but okay.  The tail sweep makes no sense though.  It is just a big club hitting them.

I also tried to use some of Svedd's special.  The Obsidian Golems were immune to crushing blow, hobble, and stun (I upgraded and got stun when I played through the first time--Save is prior to getting stun).  Again, I kind of understand hobble and stun, but crushing blow does not really make sense either.

PS   Using Growth on a Storm Dragon is awesome.

****edit****    added the game save and a few pics.

https://dl.dropbox.com/u/102157901/Obsidian%20Golem%20Bugs.EleSav

Because a Storm Dragon fighting two drakes is just fun.

Uh, that kind of sucks

No problem, just make the Storm Dragon bigger