Skirll, Embodiment of Spite

Skirll is all colors
If {w} was used to cast Skirll, Exile a random creature.
If {u} was used, return a random creature to its owner's hand.
If {b} was used, give a random creature 3 -1/-1 counters.
If {r} was used, Skirll does 3 damage to a random creature.
If {g} was used, gain 4 life.