Emptiness + Phyrexian Altar + Eternal Witness

Emptiness

Phyrexian Altar

Eternal Witness

How it works

1. Cast Emptiness for its evoke cost by paying .
2. When Emptiness enters, its first ability and evoke ability trigger.
3. Holding priority, activate Phyrexian Altar by sacrificing Emptiness, adding .
4. Resolve Emptiness's evoke trigger, failing to sacrifice it as it's no longer on the battlefield.
5. Resolve Emptiness's first trigger, returning Eternal Witness from your graveyard to the battlefield.
6. When Eternal Witness enters, it triggers, returning Emptiness from your graveyard to your hand.
7. Activate Phyrexian Altar by sacrificing Eternal Witness, adding .
8. Repeat.

This clever loop revolves around casting Emptiness for its evoke cost using white mana, then immediately sacrificing it to Phyrexian Altar to generate mana before its evoke sacrifice trigger can resolve. As Emptiness enters the battlefield, its first triggered ability brings back Eternal Witness from your graveyard, which in turn triggers upon entry to return Emptiness right back to your hand. You then sacrifice Eternal Witness to Phyrexian Altar to fuel the next casting, creating a self-sustaining cycle that continuously recycles both creatures and yields an endless chain of sacrificial and enter-the-battlefield triggers.