Necrotic Ooze, Devoted Druid, and Grim Poppet

Prerequisites

• Necrotic Ooze on the battlefield
• Devoted Druid in the graveyard
• Grim Poppet in the graveyard
• undefined

Steps

1. Activate Necrotic Ooze using Devoted Druid's first ability by tapping it, adding
2. Activate Necrotic Ooze using Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it
3. Activate Necrotic Ooze using Grim Poppet's ability by removing a -1/-1 counter from it, targeting any other creature
4. Holding priority, activate Necrotic Ooze using Devoted Druid's first ability by tapping it, adding
5. Repeat from step 2

Results

• Infinite -1/-1 counters
• Infinite green mana