Cauldron of Souls, Corridor Monitor, Verdurous Gearhulk, and Ashnod's Altar

Prerequisites

• Cauldron of Souls on the battlefield
• Corridor Monitor on the battlefield
• Verdurous Gearhulk on the battlefield
• Ashnod's Altar on the battlefield

Steps

1. Activate Cauldron of Souls by tapping it, giving Verdurous Gearhulk and Corridor Monitor persist until end of turn
2. Activate Ashnod's Altar by sacrificing Corridor Monitor, adding
3. Corridor Monitor dies, triggering its persist ability, returning itself from your graveyard to the battlefield with a -1/-1 counter on it
4. Corridor Monitor enters the battlefield, untapping Cauldron of Souls
5. Activate Ashnod's Altar by sacrificing Verdurous Gearhulk, adding
6. Verdurous Gearhulk dies, triggering its persist ability, returning itself from your graveyard to the battlefield with a -1/-1 counter on it
7. Verdurous Gearhulk enters the battlefield, putting a +1/+1 counter on itself and Corridor Monitor, and two +1/+1 counters on any other creature(s) you control
8. Repeat

Results

• Infinite +1/+1 counters on all other creatures you control
• Infinite colorless mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers