Bone Staff
Deathwish, quite common at the moment.
As Zedrix says, that staff is called Deathwish and is an exotic produced by the mystic forge. When combining 4 level 75-80-ish rare and/or exotic staffs you have a small chance to get this staff. Alternatively, you can buy one on TP, where it’s usually priced 6-10 G.
Thank you very much!