Phyrexian Altar + Thran Vigil + Lingering Tormentor

Phyrexian Altar

Thran Vigil

Lingering Tormentor

How it works

1. Activate Phyrexian Altar by sacrificing Lingering Tormentor.
2. When Lingering Tormentor 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 Lingering Tormentor.
4. Repeat.

This elegant loop turns the graveyard into a relentless engine by leveraging Phyrexian Altar to turn sacrifice outlets into an infinite flow of colored mana. Every time you feed Lingering Tormentor to the Altar, its persist ability brings it right back to the battlefield bearing a -1/-1 counter, perfectly positioned for Thran Vigil to step in. Because the Vigil watches for artifact or creature cards leaving your graveyard during your turn, the very act of persist triggering and exiting the graveyard immediately rewards you with a +1/+1 counter on Lingering Tormentor. State-based actions then cause the +1/+1 and -1/+1 counters to annihilate each other, resetting the creature so you can repeat the sacrifice all over again for endless death triggers, enter-the-battlefield triggers, and mana.