Colfenor, the Last Yew, Myr Retriever, Ashnod's Altar, and Cathodion

Prerequisites

• Colfenor, the Last Yew on the battlefield
• Myr Retriever in the graveyard
• Ashnod's Altar on the battlefield
• Cathodion on the battlefield

Steps

1. Activate Ashnod's Altar, sacrificing Cathodion to add
2. Cathodion and Colfenor trigger
3. Resolve the Cathodion trigger, adding
4. Resolve the Colfenor trigger, returning Myr Retriever from your graveyard to your hand
5. Cast Myr Retriever
6. Activate Ashnod's Altar, sacrificing Myr Retriever to add
7. Myr Retriever triggers, returning Cathodion from your graveyard to your hand
8. Cast Cathodion
9. Repeat

Results

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