Ashnod's Altar, Thran Vigil, and Persistent Constrictor

Prerequisites

• Ashnod's Altar on the battlefield
• Thran Vigil on the battlefield
• Persistent Constrictor on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Persistent Constrictor
2. When Persistent Constrictor dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. Thran Vigil triggers, putting a +1/+1 counter on Persistent Constrictor
4. Repeat

Results

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