Bosi Suru, Angel of Death

Partner with Katsui Ryoku, Angel of Life (When this creature enters the battlefield, target player may put Katsui Ryoku, Angel of Life into their hand from their library, then shuffle.)
Flying, deathtouch, trample, retribution
Insular - When Bosi Suru, Angel of Death enters the battlefield, if you spent only black mana to cast it, It gains hexproof from creatures with reach and gets lifelink.