Mortuary + Krark-Clan Ironworks + Realmwalker

Mortuary

Krark-Clan Ironworks

Realmwalker

How it works

1. Activate Krark-Clan Ironworks by sacrificing the nontoken creature, adding CC.
2. When the creature dies, Mortuary triggers, putting the creature from your graveyard onto the top of your library.
3. Cast the creature by paying its mana cost.
4. Repeat.

This loop transforms a simple loop of life and death into an endless engine by turning your library into a recycling bin. With Realmwalker naming any creature type (thanks to changeling), you gain the ability to cast that creature straight off the top of your library while constantly checking what's waiting for you there. When you sacrifice that creature to Krark-Clan Ironworks, you generate the colorless mana needed to recast it while feeding its corpse directly into Mortuary's trigger. Mortuary catches the creature as it dies and immediately places it back on top of your library, perfectly positioned for Realmwalker to pull it right back out into the open for another cycle.