Mortuary + Krark-Clan Grunt + Bolas's Citadel + Ornithopter

Mortuary

Krark-Clan Grunt

Bolas's Citadel

Ornithopter

How it works

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

This clever loop lets you sacrifice and recast a single artifact creature infinitely by turning your library into a recycling bin. With Mortuary standing guard to intercept your creature as it hits the graveyard and immediately place it back on top of your library, Bolas's Citadel steps in to let you play it right back out into the world—paying zero life for Ornithopter's mana value, completely bypassing the need for traditional mana. Meanwhile, Krark-Clan Grunt acts as the executioner and engine of the operation, giving you a continuous outlet to sacrifice Ornithopter while growing into a massive threat until end of turn.