I didn't have a problem with the invincibility. It forced me to shake up my traditional battling style and, when the enemy was completely invulnerable, it gave me a chance to withdraw and prepare myself for the next round. I also loved that the invulnerability was consistent with the laws set in the game; that was a really cool little addition.

That wyrm bastard in the desert annoyed the hell out of me, though. Immobilise is a real nuisance when you've no way to cure it!