Kayn, Shadow Reaper

Whenever a nontoken creature your opponent controls dies, exile Kayn, Shadow Reaper. If the
creature that died had greater power than
toughness, search your library for a creature card
named Kayn, Shadow Assassin, put it onto the battlefield, then shuffle, otherwise search your
library for a creature card named Rhaast, Darkin Scythe, put it onto the battlefield, then shuffle.