I would reduce the bonus to Hide, Move Silently, Spot and Search to 1/2 class level.

I would include the Poison Use (standard action) and Improved Poison Use (move action) abilities, and grant a normal DC progression for the Death Attack (10 + 1/2 class level + Int Mod)

I would do away with the abilities to grant allies darkvision/blindsense and put Darkvision on the spell list.