Mortuary + Goblin Bombardment + Bolas's Citadel + Ornithopter

Mortuary

Goblin Bombardment

Bolas's Citadel

Ornithopter

How it works

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

This loop turns free artifacts into an endless engine of destruction by turning your graveyard into a revolving door. You begin by using Goblin Bombardment to sacrifice Ornithopter, dealing damage while triggering Mortuary to seamlessly recycle the tiny thopter straight back to the top of your library. From there, Bolas's Citadel steps in as the ultimate enabler, allowing you to bypass mana costs entirely and cast Ornithopter directly from the top of your deck for zero life, ready to be sacrificed all over again.