Mori Calliope, Shinigami

Flying, deathtouch

At the beginning of each upkeep, that player sacrifices a creature of their choice.

Whenever a permanent is sacrificed, put a +1/+1 counter on Mori.

While Mori has 10 or more counters, they gain the following ability: "Whenever Mori deals combat damage to a player, that player loses the game."