Testament, Elegant Grim Reaper

At the beginning of your end step, you may create Unholy Diver, a legendary 1/1 black Bird creature token with flying and “Whenever this creature deals combat damage to
a player, you may put a Stain counter on target permanent or player that doesn’t have a Stain counter on
it.”

Whenever a source you control not named Unholy Diver deals damage to a permanent or player, you may remove a Stain counter from it. When you do, Testament deals 2 damage to that permanent or player.