Heart of Corruption

Heart of Corruption enters the battlefield tapped.
{t}: Add {b} to your mana pool.
{t}, Pay 1 life: Add {r} or {g} to your mana pool.
{3}{b}{r}{g}, {t}, Sacrifice Heart of Corruption: Put
a +1/+1 counter on target tapped creature you control, then each opponent loses life equal to that creature's power. Activate this ability only
any time you could activate a sorcery.