Enduring Renewal + Phyrexian Altar + Cubwarden + Planar Gate

Enduring Renewal

Phyrexian Altar

Cubwarden

Planar Gate

How it works

1. Cast Cubwarden for its mutate cost by paying , targeting a non-Human creature you control.
2. The Cubwarden mutated creature triggers, creating two 1/1 Cat creature tokens.
3. Activate Phyrexian Altar by sacrificing the Cubwarden mutated creature, adding .
4. When the Cubwarden mutated creature dies, Enduring Renewal triggers, returning Cubwarden and any cards merged with it from your graveyard to your hand.
5. Activate Phyrexian Altar by sacrificing a Cat token, adding .
6. Repeat.

This clever loop relies on Enduring Renewal's replacement and trigger effects to turn your graveyard into an extension of your hand for a single creature. By using Planar Gate to discount your spells and Phyrexian Altar to sacrifice your creatures for mana, you can recast Cubwarden repeatedly. Every time Cubwarden enters and mutates, it triggers to create two Cat tokens, providing the extra fodder needed to keep the loop fueled and generating infinite sacrifices, triggers, and storm count.