Silex, the Dreamwaker

+2: Create a 2/2 colorless Nightmare creature token. All Nightmares you control gain a choice of Flying, Hexproof or Deathtouch until your next turn.
-X: Until your next turn, increases the cost of all opponent's spells and activated abilities by X and reduce the cost of all spells you cast by X.
-7: Choose up to seven permanents. They become Nightmares in addition to their other types. Gain control of all Nightmares.