Ancient Adamantoise + Nim Deathmantle + Umbral Collar Zealot + Archelos, Lagoon Mystic

Ancient Adamantoise

Nim Deathmantle

Umbral Collar Zealot

Archelos, Lagoon Mystic

How it works

1. Activate Umbral Collar Zealot by sacrificing Ancient Adamantoise.
2. When Ancient Adamantoise dies, it and Nim Deathmantle trigger.
3. Resolve the Nim Deathmantle trigger, causing you to pay 4 to return Ancient Adamantoise from your graveyard to the battlefield and attach Nim Deathmantle to it.
4. Resolve the Ancient Adamantoise trigger, creating ten Treasure tokens that enter untapped due to Archelos.
5. Resolve the Umbral Collar Zealot ability.
6. Activate four Treasures by tapping and sacrificing them, adding 4.
7. Repeat.

This loop centers around Ancient Adamantoise, whose redirection ability and death trigger make it a massive engine when paired with Nim Deathmantle. By using Umbral Collar Zealot to sacrifice Ancient Adamantoise, you send it to the graveyard, which triggers Nim Deathmantle's ability to resurrect it for four mana. When Ancient Adamantoise dies, it also yields ten Treasure tokens that easily pay for that resurrection cost, while Archelos, Lagoon Mystic ensures those Treasures enter the battlefield untapped so they can be immediately tapped and sacrificed back to Umbral Collar Zealot for a net gain of mana and infinite resources.