Blackflame

As an additional cost to cast this spell, you may exile a multicolored spell from your hand. If you do, this spell gains Plague. (As this spell resolves exile it. Then return it to the battlefield under your control as an Enchantment with "At the beginning of your upkeep" prepended to the card's text)

Blackflame deals 3 damage to any target unless that target's controller or player sacrifices a
nonland permanent or discards a card.