Mortuary + Grim Haruspex + Omarthis, Ghostfire Initiate

Mortuary

Grim Haruspex

Omarthis, Ghostfire Initiate

How it works

1. Cast Omarthis by paying 0.
2. Omarthis enters and dies as a state-based action due to having 0 toughness, triggering Mortuary and Grim Haruspex.
3. Resolve the Mortuary trigger, putting Omarthis from your graveyard onto the top of your library.
4. Resolve the Grim Haruspex trigger, causing you to draw a card, thus drawing Omarthis from your library.
5. Repeat.

By casting Omarthis, Ghostfire Initiate for zero mana, you immediately send it to the graveyard as a state-based action, which acts as the spark for this entire engine. This death triggers Grim Haruspex to draw you a card, while Mortuary simultaneously catches Omarthis on its way down and places it right back on top of your library. Because the draw step naturally puts Omarthis back into your hand, you are set up to instantly replay it and repeat the loop for infinite death triggers and card draws.