Mortuary + Phyrexian Altar + Bolas's Citadel + Ornithopter

Mortuary

Phyrexian Altar

Bolas's Citadel

Ornithopter

How it works

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

This elegant loop revolves around the zero-mana cost of Ornithopter, which lets you cast it for free off the top of your library using Bolas's Citadel without paying any life at all. Once on the battlefield, you can immediately sacrifice that same Ornithopter to Phyrexian Altar to generate a mana of any color. That sacrifice triggers Mortuary, which steps in to ensure Ornithopter never stays in the graveyard, instantly placing it back on top of your library so Bolas's Citadel can reveal it once more. Repeating this cycle yields an infinite storm count, endless deaths, and limitless colored mana to fuel whatever devastating win condition you desire.