Ara'Ki, The Soul Collector

Whenever a creature leaves the battlefield or enters the graveyard, Ara'Ki, The Soul Collector gains +X/+Y until end of turn where X is that creatues toughness and Y is that creatures power. Only two creatures can have +X/+Y from this at once.
{u}{b}: Instead of Ara'Ki, The Soul Collector, another target creature you control gains +X/+Y until end of turn instead.