Mikaeus, the Unhallowed, Putrid Goblin, and Ashnod's Altar

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Putrid Goblin on the battlefield
• Ashnod's Altar on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Putrid Goblin, adding
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. Activate Ashnod's Altar by sacrificing Putrid Goblin, adding
6. Putrid Goblin dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it
7. Activate Ashnod's Altar by sacrificing Putrid Goblin, adding
8. Putrid Goblin dies, triggering its persist ability, returning it from your graveyard to the battlefield with a -1/-1 counter on it
9. Repeat from step 5

Results

• Infinite colorless mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers