Giant Oyster

Creature - Oyster 0/3, 2UU (4)
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.¹
Illus. Nicola Leonard

Crystal Keep Rulings Summaries

• A -1/-1 counter is added to the creature each of your draw steps. [D'Angelo 2006/10/08]
• If the Oyster untaps during draw step before its ability to add a -1/-1 counter resolves, the -1/-1 counter effect resolves and adds a -1/-1 counter after the -1/-1 counters are removed due to being untapped. [D'Angelo 2000/02/15]

Format Legality	Legal in Vintage, Legacy, Extended Banned in Standard
Printings (2/15)	Time Spiral Timeshifted (Special) Homelands (Uncommon)