Teval, the Balanced Scale + Extractor Demon + Ashnod's Altar + Sundering Archaic

Teval, the Balanced Scale

Extractor Demon

Ashnod's Altar

Sundering Archaic

How it works

1. Activate Ashnod's Altar by sacrificing another creature, adding CC.
2. When the creature dies, Extractor Demon triggers, causing you to mill two cards if your graveyard is empty, or causing an opponent to mill two cards otherwise.
3. If your library is empty, activate [[Permanent with "Pay Mana: Put target card from your graveyard on the bottom of your library"]] by paying 2, putting a card from your graveyard onto the bottom of your library.
4. Teval triggers, creating a 2/2 Zombie Druid creature token.
5. Repeat.

This intricate self-sustaining loop relies on Ashnod's Altar to constantly convert creatures into colorless mana while feeding the graveyard for Teval, the Balanced Scale to reap token rewards whenever cards depart from it. As creatures die to the Altar, Extractor Demon triggers to fuel the graveyard further, creating the exact graveyard-leaving events that Teval, the Balanced Scale needs to continuously spawn 2/2 Zombie Druid tokens to be sacrificed right back into the engine. Meanwhile, Sundering Archaic's active ability steps in to recycle cards from your graveyard back to the bottom of your library for just {2}, preventing you from decking out and keeping the infinite loop rolling indefinitely.