Necrotic Ooze, Boa Constrictor, and Barrenton Medic

Prerequisites

• Necrotic Ooze on the battlefield
• Boa Constrictor in the graveyard
• Barrenton Medic in the graveyard
• Necrotic Ooze does not have summoning sickness
• It is your precombat main phase

Steps

1. Activate Necrotic Ooze using Boa Constrictor's ability by tapping it, giving it +3/+3 until end of turn
2. Activate Necrotic Ooze using Barrenton Medic's second ability by putting a -1/-1 counter on it, untapping it
3. Repeat

Results

• Infinitely large Necrotic Ooze until end of turn