Korron, Elemental Avatar

+3: Put a 5/5 Elemental with Flying, First Strike, and Trample that's green, blue, and red onto the battlefield.
-4: Draw a card for each creature you control. Those creatures get +X/+X until end of turn. X=# of cards in your Hand.
-10: Korron deals 7 damage to target creature or player. Return up to 7 target creatures to hand. May tutor creature of CMC 7 or less onto battlefield