Hofri Ghostforge + Moorland Rescuer + Phyrexian Altar

Hofri Ghostforge

Moorland Rescuer

Phyrexian Altar

How it works

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