Phyrexian Altar + Restless Apparition + Thran Vigil

Phyrexian Altar

Restless Apparition

Thran Vigil

How it works

1. Activate Phyrexian Altar by sacrificing Restless Apparition.
2. When Restless Apparition 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 Restless Apparition.
4. Repeat.

This clever loop centers on the recursive nature of Restless Apparition, which feeds itself directly to Phyrexian Altar to generate an endless stream of colored mana and death triggers. Because persist returns the spirit with a -1/-1 counter, Thran Vigil steps in during your turn to place a countering +1/+1 counter on it whenever it leaves the graveyard, effectively neutralizing the penalty through the rules for countering +1/-1 and +1/+1 counters. This ensures that every time Restless Apparition meets its end at the Altar, it returns clean and ready to be sacrificed all over again.