Shrevian, Life Balancer

+3: Each player discards a card, then draws a card. Each player gains 2 life. Each player scry 1.
-2: Each player sacrifices a creature. If the creature you sacrificed was a balance enchantment, target player sacrifices another creature.
-15: Put any number of cards from the top of your library into your graveyard, then target opponent sacrifices that many permanents.