Mortuary + Bolas's Citadel + Viscera Seer + Syr Vondam, Sunstar Exemplar

Mortuary

Bolas's Citadel

Viscera Seer

Syr Vondam, Sunstar Exemplar

How it works

1. Activate Viscera Seer by sacrificing it.
2. When Viscera Seer dies, Mortuary and Syr Vondam trigger.
3. Resolve the Mortuary trigger, putting Viscera Seer from your graveyard onto the top of your library.
4. Resolve the Syr Vondam trigger, causing you to gain 1 life and putting a +1/+1 counter on Syr Vondam.
5. Resolve the Viscera Seer ability.
6. Cast Viscera Seer from the top of your library by paying 1 life.
7. Repeat.

This crafty loop relies on Mortuary to intercept your creatures as they die and seamlessly redirect them back to the top of your library. From there, Bolas's Citadel allows you to simply replay that creature straight off the top, turning life totals into a resource while Viscera Seer provides the zero-mana sacrifice outlet needed to keep the cycle spinning. Meanwhile, Syr Vondam, Sunstar Exemplar sits back and rewards your endless loop by accumulating an infinite number of +1/+1 counters and life every time a creature heads to the graveyard.