Shagrat

Menace (This creature can't be blocked except by
two or more creatures.)
Whenever Shagrat deals combat damage to a
player, look at the top three cards of that player's
library, exile one of them face down, then put
the rest into their graveyard. You may look at
and cast that card for as long as it remains exiled,
and you may spend mana as though it were mana
of any type to cast that spell.