Nim Deathmantle + Ashnod's Altar + Tangled Colony + Pandemonium

Nim Deathmantle

Ashnod's Altar

Tangled Colony

Pandemonium

How it works

1. Activate Ashnod's Altar by sacrificing Tangled Colony, adding CC.
2. When Tangled Colony dies, it and Nim Deathmantle triggers.
3. Resolve the Nim Deathmantle trigger from step 2, causing you to pay 4 to return Tangled Colony from your graveyard to the battlefield, and attach Nim Deathmantle to it.
4. When Tangled Colony enters the battlefield, Pandemonium triggers, dealing damage equal to Tangled Colony's power to any target.
5. Resolve the Tangled Colony trigger, creating a 1/1 Rat creature token.
6. When the Rat enters the battlefield, Pandemonium triggers, dealing 1 damage to Tangled Colony.
7. Activate Ashnod's Altar by sacrificing the Rat, adding CC.
8. Repeat.

This delightful loop turns Tangled Colony into an endless self-sustaining engine by taking advantage of the damage it takes from Pandemonium. When you sacrifice Tangled Colony to Ashnod's Altar, Nim Deathmantle steps in to resurrect it for four mana, a cost easily paid using the altar's own sacrifice proceeds. As Tangled Colony re-enters, Pandemonium triggers to strike it for one damage, which cleverly powers up Tangled Colony's own death trigger to create a 1/1 Rat token. Sacrificing that Rat to Ashnod's Altar provides the remaining mana needed to sustain the loop while letting you continually trigger Pandemonium for endless damage.