Mortuary + Ravenous Intruder + Bolas's Citadel + Ornithopter

Mortuary

Ravenous Intruder

Bolas's Citadel

Ornithopter

How it works

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

This ingenious engine uses Bolas's Citadel to cast Ornithopter directly from the top of your library for zero life, completely bypassing traditional mana costs. Once that free artifact is on the battlefield, Ravenous Intruder happily devours it for a snack, triggering Mortuary to instantly tuck Ornithopter right back onto the top of your library. Because Bolas's Citadel lets you play the top card of your library at will, you can repeat this sacrifice-and-draw loop indefinitely to pump Ravenous Intruder into a towering threat while racking up infinite death triggers and storm count.