Rules Text Contains: You may choose not to untap Giant Oyster during your untap step.
T: As long as Giant Oyster remains tapped, target tapped creature doesn't untap during its controller's untap step, and at the beginning of each of your draw steps, put a -1/-1 counter on that creature. When Giant Oyster leaves play or becomes untapped, remove all -1/-1 counters from the creature.
