Vilitch and Thomin, the Twins

Whenever Vilitch and Thomin attacks, exile
the top card of each player’s library, then you
may cast any number of spells from among
those cards without paying their mana costs.

"The Architect could have changed me, given I alone have a body packed with muscle. Instead
he gave me my brother's. This I knew was the
boon, because that's how I learnt to dominate..."