Mortuary + Ravenous Intruder + Memnite + Bolas's Citadel

Mortuary

Ravenous Intruder

Memnite

Bolas's Citadel

How it works

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

This loop uses Bolas's Citadel as the ultimate engine, allowing you to cast spells directly from the top of your library by paying life instead of mana. Memnite is the zero-cost fuel for this fire, dropping back onto the battlefield for free over and over again. Every time you feed that little automaton to Ravenous Intruder, Mortuary steps in to instantly intercept the creature card on its way to the graveyard and place it right back on top of your library. The result is an indefinitely repeating cycle that pumps Ravenous Intruder to astronomical proportions while racking up infinite storm count, deaths, and sacrifice triggers.