Kirby, Star Warrior

Whenever Kirby, Star Warrior dealt damage to a creature, Kirby gets +X/+X where X is the converted mana cost of that creature if that creature died this turn.
{x}{x}{x}: Exile X creatures. For each creature exiled with Kirby, Kirby gets +X/+X until the
end of the turn where X is that creature's converted mana cost. On your end step, return those creatures to the battlefield under their owners' control.