Cavalier of Night + Activated Sleeper + Phyrexian Altar

Cavalier of Night

Activated Sleeper

Phyrexian Altar

How it works

1. Activate Phyrexian Altar by sacrificing Cavalier of Night, adding one mana of any color.
2. When Cavalier of Night dies, it triggers, returning Activated Sleeper from your graveyard to the battlefield as a copy of Cavalier of Night.
3. When Activated Sleeper enters the battlefield, it triggers; choose not to sacrifice a creature.
4. Activate Phyrexian Altar by sacrificing Activated Sleeper, adding one mana of any color.
5. When Activated Sleeper dies, it triggers, returning Activated Sleeper from your graveyard to the battlefield as a copy of Cavalier of Night.
6. Repeat from step 3.