Blackdeath Hydra

Double strike, Reach
At the beginning of your end step, put a Weaken
counter on Blackdeath Hydra. When Blackdeath
Hydra has 3 Weaken counters on it, sacrifice it.
Whenever Blackdeath Hydra dies, shuffle it
into its owner's library.
When Blackdeath Hydra is played for the third
time, you win the game.