How do you plan to deal with HP regeneration between combat encounters and is there "permanent death" like in the IE games? Also is there some sort of mana or other magic resource required for casting spells?
I haven't thought through a lot of the details, but I was considering something similar to Darklands, where characters have both Endurance and Health. Most damage taken in combat would Endurance, which is relatively easy to restore (through abilities and magic) and regenerates rapidly on its own, both in and out of combat. Damage to Health would be more serious and much harder to restore (probably only through consumables and/or rest). Having your Endurance lowered to 0 would knock the character out. Having your Health knocked to 0 would kill the character outright (though there may be some optional, lesser version of this effect for non-Expert players).
We've talked about characters having a mana-like soul resource for using abilities, but I don't know that it's necessary.