Killian, Ink Duelist + Enduring Renewal + Phyrexian Altar + Cubwarden

Killian, Ink Duelist

Enduring Renewal

Phyrexian Altar

Cubwarden

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 ingenious loop relies on Killian, Ink Duelist to drastically slash the cost of casting Cubwarden for its mutate ability, turning it into a bargain at just two white mana. Once cast, the mutated creature triggers to generate a pair of Cat tokens, which can be sacrificed to Phyrexian Altar alongside the mutated stack itself to generate the mana needed to repeat the process. Finally, Enduring Renewal ensures that every time the Cubwarden stack hits the graveyard, it seamlessly bounces right back to your hand, ready to mutate all over again and keep the chain going indefinitely.