Balofuri, Mana Gorger

{w}{u}{b}{r}{g}: Balofuri becomes a color of your choice until end of turn. If it blocks or becomes blocked by a creature of the same color, exile that creature and place a +1/+1 counter on Balofuri.
If Balofuri's power becomes higher than half your life total, sacrifice it. It does damage equal to its toughness to each creature.