I have a level 38 Necro/Dark MM, and the one power, I have slotted for - to Hit, is Fearsome Stare, this is always my opener. You also have Shadow Fall, Weave, Maneuvers, in which fully slotted with IO's and the - to Hit from Fearsome Stare, is massive. I am not too familiar with Demons, but I run Necro, and everything is - to Hit, which locks down mobs or AV's easily. Correct me if I am wrong, but I do believe you have some pretty sweet resistances, with Demon, they must be pretty tanky, even with all the MM, resist and defense auras. Dr. Casualty I believe had it right, a Resist Armor is always better to Pad the damage, because the Pets will wipe, with a strong spike from an AV.