Mortuary + Krark-Clan Grunt + Ornithopter + Gwenom, Remorseless

Mortuary

Krark-Clan Grunt

Ornithopter

Gwenom, Remorseless

How it works

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

This loop leverages Gwenom, Remorseless to turn the top of your library into an alternative casting zone, allowing you to pay zero life to cast spells revealed there. Whenever Ornithopter is sacrificed to fuel Krark-Clan Grunt's ability, Mortuary's static trigger catches the little flyer on its way to the graveyard and immediately places it back on top of your library. From there, Gwenom lets you replay the Ornithopter for free, repeating the cycle to generate infinite death triggers, enter-the-battlefield triggers, and an overwhelmingly massive Krark-Clan Grunt.