Time Spiral Timeshifted

Giant Oyster

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.

You may choose not to untap Giant Oyster during your untap step.
{T}: For 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 the battlefield or becomes untapped, remove all -1/-1 counters from the creature.

Homelands

You may choose not to untap Giant Oyster during your untap phase.
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T: Target tapped creature does not untap during its controller's untap phase as long as Giant Oyster remains tapped. During your upkeep, put a -1/-1 counter on that creature. If Giant Oyster becomes untapped or leaves play, remove all these counters from the creature.