Hofri Ghostforge, Mistmoon Griffin, and Ashnod's Altar

Prerequisites

• Hofri Ghostforge on the battlefield
• Mistmoon Griffin on the battlefield
• Ashnod's Altar on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Mistmoon Griffin, adding
2. Mistmoon Griffin dies, triggering itself and Hofri Ghostforge
3. Resolve the Hofri Ghostforge trigger, exiling Mistmoon Griffin from your graveyard and creating a token copy of Mistmoon Griffin that has "When this creature leaves the battlefield, return the exiled card to your graveyard"
4. Resolve the Mistmoon Griffin trigger, returning nothing from your graveyard to the battlefield
5. Activate Ashnod's Altar by sacrificing the Mistmoon Griffin token, adding
6. The Mistmoon Griffin token dies, triggering itself twice
7. Resolve the Mistmoon Griffin token's trigger granted by Hofri Ghostforge, returning Mistmoon Griffin from exile to your graveyard
8. Resolve the other Mistmoon Griffin trigger, returning Mistmoon Griffin from your graveyard to the battlefield
9. Repeat

Results

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