Nim Deathmantle + Ashnod's Altar + Voracious Vermin

Nim Deathmantle

Ashnod's Altar

Voracious Vermin

How it works

1. Activate Ashnod's Altar by sacrificing Voracious Vermin, adding CC.
2. When Voracious Vermin dies, it and Nim Deathmantle triggers.
3. Resolve the Voracious Vermin trigger, creating a 1/1 Rat creature token.
4. Activate Ashnod's Altar by sacrificing the Rat, adding CC.
5. Resolve the Nim Deathmantle trigger from step 2, causing you to pay 4 to return Voracious Vermin from your graveyard to the battlefield, and attach Nim Deathmantle to it.
6. Repeat.

This clever loop is powered by Ashnod's Altar, which conveniently converts the exact mana needed to fuel Nim Deathmantle's resurrection ability each time a creature is sacrificed. When you sacrifice Voracious Vermin to the Altar, its death triggers along with the Deathmantle, allowing you to easily generate the required four generic mana by also discarding the token it creates. As Voracious Vermin enters the battlefield over and over, it replaces itself with a fresh Rat token to sacrifice, letting you repeat this cycle indefinitely for an endless stream of deaths and sacrifices.