Mask of Tengu
The key with this one is heavy damage paired with potent life steal. The Type-A booster adds an extra 100(+80% spell bonus) to your next normal attack with a two second cooldown after you cast a skill, and Viru's second skill has a two second cooldown. The True Staff has a passive spell life steal that will drain whenever Viru casts damage, so paired with his third skill, this makes him hard to take down. This build also raises his SP ridiculously high.