Koth, Made Corporeal

: (X is the colorless converted mana cost of all nonland permanents on the battlefield.)
+2: Pay two colorless mana to use this ability. This ability can be activated more than once each turn, in addition to Koth's -10 ability.
-10: Gain control of a permanent on the battlefield and reveal an Eldrazi card from your hand. That permanent becomes a copy of the revealed card.