Kyubey

Kyubey enters the battlefield with 20 entropy counters. When there are no entropy counters on Kyubey, you win the game.
Whenever damage is dealt to a magical-girl you control, you may pay {1}. If you do, remove an
entropy counter from Kyubey, otherwise,
sacrifice that creature and target opponent
creates a 3/3 colorless witch creature token with "Whenever damage is dealt to this creature, put a
+1/+1 counter on it."