Mortuary + Viscera Seer + Bolas's Citadel + Ornithopter

Mortuary

Viscera Seer

Bolas's Citadel

Ornithopter

How it works

1. Activate Viscera Seer by sacrificing Ornithopter
2. When Ornithopter dies, Mortuary triggers, putting Ornithopter from your graveyard onto the top of your library.
3. Resolve the Viscera Seer ability.
4. Cast Ornithopter from the top of your library by paying 0 life.
5. Repeat.

This clever loop turns zero-mana creatures into an engine of endless iteration by combining the battlefield positioning of Bolas's Citadel with a precise recycling loop. When you sacrifice Ornithopter to Viscera Seer, Mortuary steps in to instantly catch the creature as it hits the graveyard and place it right back on top of your library. From there, Bolas's Citadel allows you to cast Ornithopter directly off the top for zero life, resetting the entire sequence to generate infinite deaths, sacrifices, and scrys.