This game isn't hard...unless you play a mage. Every difficulty level is 2 slots ahead of the regular one. After Master, if you play a mage, there is a Masochistic level and an Insane level.
Uhh... what? I think you're doing it wrong then. Master is hard for a mage early on because your mana efficiency isn't good enough to kill very many enemies when they have increased health, but once you've got some decent spell casting gear, a good staff, and a Black Star or Azura's Star, you can start dominating. You know you're powerful when on master difficulty your level 28 wizard can take out a level 40 elder dragon (though I haven't downloaded any of the patches so my magic resistance actually protects properly against breath weapon).
I think the only time I've died in recent memory is when I got jumped by a sabre cat and wasn't really paying attention, and when a vampire's thrall got resurrected behind me and two shot me. Enemies increase damage is only relevant if they can get close enough to you.