Hogaak, Arisen Necropolis + Altar of Dementia + Golgari Germination + The Skullspore Nexus

Hogaak, Arisen Necropolis

Altar of Dementia

Golgari Germination

The Skullspore Nexus

How it works

1. Activate Altar of Dementia by sacrificing Hogaak.
2. When Hogaak dies, Golgari Germination and The Skullspore Nexus trigger, creating two creature tokens.
3. Resolve the Altar of Dementia ability, causing you to mill eight cards.
4. Cast Hogaak from your graveyard by exiling five cards from your graveyard and tapping two black and/or green creatures you control.
5. Repeat.

This macabre loop relies on Hogaak, Arisen Necropolis being cast directly from your graveyard for zero mana using its delve and convoke abilities, bypassing the restriction that you can't spend mana to cast it. Each iteration begins by feeding Hogaak to Altar of Dementia to mill eight cards, filling your graveyard for the next casting while triggering Golgari Germination and The Skullspore Nexus. Those enchantment and artifact triggers replace the sacrificed horror by spitting out a 1/1 Saproling and a massive Fungus Dinosaur token, which simultaneously provide the creatures needed to convoke Hogaak back from the dead.