Stet, Draconic Proofreader

Flying

Whenever this creature deals combat damage to a player, exile that many cards from the top of your library. Until end of turn, you may cast spells from among those exiled cards.

Flying

Whenever Dragonhawk enters or attacks, exile the top X cards of your library, where X is the number of creatures you control with power 4 or greater. You may play those cards until your next end step. At the beginning of your next end step, Dragonhawk deals 2 damage to each opponent for each of those cards that are still exiled.

Flying

: This creature gets +1/+0 until end of turn.

Whenever this creature deals combat damage to a player, you may have it deal that much damage to target creature that player controls.

Flying, trample

Join forces — Whenever this creature attacks or blocks, each player starting with you may pay any amount of mana. This creature gets +X/+0 until end of turn, where X is the total amount of mana paid this way.

Trample

When Themberchaud enters, he deals X damage to each other creature without flying and each player, where X is the number of Mountains you control.

You may exert Themberchaud as he attacks. When you do, he gains flying until end of turn. (An exerted creature won't untap during your next untap step.)

Flying

Whenever you cast a spell from exile, copy it. You may choose new targets for the copy. If it's a permanent spell, the copy gains haste and "At the beginning of the end step, sacrifice this permanent." (A copy of a permanent spell becomes a token.)