Mortuary + Narcomoeba + Undercity Informer + Sifter of Skulls

Mortuary

Narcomoeba

Undercity Informer

Sifter of Skulls

How it works

1. Activate Undercity Informer by paying 1 and sacrificing Narcomoeba.
2. When Narcomoeba dies, Mortuary and Sifter of Skulls trigger.
3. Resolve the Mortuary trigger, putting Narcomoeba on top of your library from your graveyard.
4. Resolve the Sifter of Skulls trigger, creating a 1/1 Eldrazi Scion creature token.
5. Resolve the Undercity Informer ability, causing you to put Narcomoeba into your graveyard from the top of your library.
6. Narcomoeba triggers, returning itself to the battlefield from your graveyard.
7. Activate the Eldrazi Scion by sacrificing it, adding C.
8. Repeat.

This loop turns a simple self-mill engine into a closed-circuit machine by weaponizing the interaction between library and graveyard. When you sacrifice Narcomoeba to the activation cost of Undercity Informer, Sifter of Skulls steps in to replace that lost body by spawning an Eldrazi Scion, which can then be sacrificed for the mana needed to keep the Informer running. Meanwhile, Mortuary catches Narcomoeba as it hits the graveyard and neatly places it back on top of your library, ensuring the Informer's mill effect instantly finds it again and triggers its ability to return directly to the battlefield.