Xexeru, Vengeful Manticore

Flying, Haste
{2}{p/w}{p/b}{p/r}: Put Xexeru, Vengeful Manticore from your graveyard or command zone onto the battlefield under your control. If you do, it loses haste.
When a creature you control dies, Xexeru deals X damage to each opponent where X is that creatures converted mana cost.