Mortuary + Altar of Dementia + Bolas's Citadel + Ornithopter

Mortuary

Altar of Dementia

Bolas's Citadel

Ornithopter

How it works

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

This elegant loop lets you completely mill out your opponents by recycling a single free artifact creature over and over again. You begin by using Altar of Dementia to sacrifice Ornithopter, which triggers Mortuary to immediately tuck the tiny flyer right back onto the top of your library. From there, Bolas's Citadel steps in as the engine's beating heart, allowing you to bypass mana costs and recast Ornithopter directly from the top of your deck by paying 0 life. Because Mortuary replaces the graveyard trip with a library placement, the Citadel can keep casting the exact same Ornithopter ad infinitum to continuously mill your opponents away.