The game is HUGE! I never did finish it.
I played as a mage (of some kind) that specialized in electricity. Little did I know that demons are flat-out immune to electricity attacks. They did provide a mechanic that lets you overcome that resistance, but it sure made for a rough start.
Specializing in poison attacks is another no-no. (Though, I remember something about some patches helping with that. It was after I stopped playing, so I don't know the details.)