Undercity Plague [Gatecrash]

Set: Gatecrash Type: Sorcery Rarity: Rare Cost: {4}{B}{B} Target player loses 1 life, discards a card, then sacrifices a permanent.Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)