Cthulhu, Arisen Sleeper

Eminence: At the beginning of each players upkeep
that player exiles a card from the top of their libary.

Indistructible, Hexproof, Cant be countered
Cthulhu, Arisen Sleeper costs {1} less to cast for each
card in exile.
When Cthulhu, Arisen Sleeper enters the battlefield
or attacks you may cast a spell from exile without
paying its mana cost.

You can not take extra turns.