Mikaeus, the Unhallowed, Putrid Goblin, and Carrion Feeder

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Putrid Goblin on the battlefield
• Carrion Feeder on the battlefield

Steps

1. Activate Carrion Feeder by sacrificing Putrid Goblin
2. Putrid Goblin dies, triggering its persist and undying abilities
3. Resolve the persist trigger, returning it from your graveyard to the battlefield with a -1/-1 counter on it
4. Resolve the undying trigger, doing nothing
5. Resolve the Carrion Feeder ability, putting a +1/+1 counter on it
6. Activate Carrion Feeder by sacrificing Putrid Goblin
7. Putrid Goblin dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it
8. Resolve the Carrion Feeder ability, putting a +1/+1 counter on it
9. Activate Carrion Feeder by sacrificing Putrid Goblin
10. Putrid Goblin dies, triggering its persist ability, returning it from your graveyard to the battlefield with a -1/-1 counter on it
11. Repeat from step 5

Results

• Infinite +1/+1 counters on Carrion Feeder
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers