Demonic Transformation

enchanted creature has +4/+2, trample, protection from white and is a demon in addition to other types.
{x}: enchanted creature gets +X/+0. if enchanted creature deals combat damage to a player, another target creature gets -0/-X.
when enchanted creature deals combat damage to a player put a +1/+1 counter on it and you get {e}.
pay {e}{e}{e}{e}: destroy target creature.