Prerequisites
- Cauldron of Souls on the battlefield
- Corridor Monitor on the battlefield
- Cathars' Crusade on the battlefield
- Ashnod's Altar on the battlefield
- Corridor Monitor does not have a -1/-1 counter on it
Steps
- Activate Cauldron of Souls by tapping it, giving Corridor Monitor persist until end of turn
- Activate Ashnod's Altar by sacrificing Corridor Monitor, adding
- When Corridor Monitor dies, its persist ability triggers, returning itself from your graveyard to the battlefield with a -1/-1 counter on it
- When Corridor Monitor enters the battlefield, it and Cathars' Crusade trigger
- Resolve the Corridor Monitor trigger, untapping Cauldron of Souls
- Resolve the Cathars' Crusade trigger, putting a +1/+1 counter on each creature you control
- Repeat
Results
- Infinite colorless mana
- Infinite death triggers
- Infinite ETB
- Infinite LTB
- Infinite sacrifice triggers
- Infinite +1/+1 counters
Required Cards 4
Corridor Monitor
Artifact Creature — Construct
Cathars' Crusade
Enchantment