Namor the Sub-Mariner + Phyrexian Altar + Whispers of the Muse + Will, Scion of Peace

Namor the Sub-Mariner

Phyrexian Altar

Whispers of the Muse

Will, Scion of Peace

How it works

1. Activate Will by tapping it.
2. Cast Whispers of the Muse by paying due to Will.
3. Namor triggers, creating a 1/1 Merfolk creature token.
4. Resolve Whispers of the Muse.
5. Activate Phyrexian Altar by sacrificing the Merfolk, adding .
6. Repeat from step 2.

This clever loop relies on Will, Scion of Peace heavily discounting your spells, allowing you to cast Whispers of the Muse for just a single blue mana. Once cast, Namor the Sub-Mariner catches the blue mana symbols in the spell's cost and churns out a 1/1 Merfolk token to reward your noncreature spellcasting. You can then feed that fresh token directly into Phyrexian Altar to generate the exact mana needed to pay for the next iteration. Because Whispers of the Muse draws a card upon resolution, you seamlessly cycle through your entire deck while continuously churning your sacrifice engine.