Tiezzum, Dragon Lord

+2: Draw a card. You may deal X damage to target creature or planeswalker where X is the drawn card's converted mana cost.
-X: Repeat this process X times: Each opponent exiles a card from their hand or a permanent they control. Each opponent who doesn't looses 4 life.
-12: Exile the top 20 cards of Target player's library. You may play them this turn without paying their mana cost.