Maybe damage reduction ought to be more discriminatory about what types of damage it reduces? For instance...

Elemental invoker shields. There's a logical reason that it would reduce physical damage according to the laws of magic and whatnot. But divine types like wrath and defilement? Mental attacks? Bone disruptions?

Sanctuary, barrier and bard song resisting I could see reducing all types of damage, even aura and shield too. Black sanc should not offer more damage reduction than sanc does against defilement attack type.

Stone skin has no logical reason to reduce the attacks of wrath, mental and some forms of elemental damage. Neither do various transmuter damage reduction options for similar reasons.

Rager's resist cabal power should probably not defend against mental damage so well, however the argument for physical is obvious, followed by the fact that divine is every bit as physically manifested as magic. But mental assaults aren't.

Anyway I just thought I'd toss the idea out there. It would add more strategy to having various types of weapons out there and maybe even open up the door to more mental assault weapon attacks.

And Chaotic Blast attack type should get around ALL damage reduction for the simple reason that it doesn't follow the rules and Entropy always had the potential to be bad-ass.

Also, are the ways to physically attack mana being thought about too? I'd like to see cranial doing 50 mana damage or so each hit to the head in addition to the int loss effect, stuff like that. Or maybe weapons that prog draining mana or energy drain.