Blightbeetle + Thermopod + Zedruu the Greathearted

Blightbeetle

Thermopod

Zedruu the Greathearted

How it works

1. Donate Blightbeetle to an opponent
2. Activate Thermopod by sacrificing the undying creature.
3. When the undying creature dies, its undying ability triggers, returning itself from your graveyard to the battlefield without a +1/+1 counter on it due to Blightbeetle.
4. Repeat from step 2.

This ingenious loop lets you wring infinite red mana and death triggers from an undying creature by weaponizing Blightbeetle's passive static ability against your own side of the table. Normally, an undying creature returns with a +1/+1 counter that shuts down further recursion, but because you use Zedruu the Greathearted to donate the Blightbeetle to an opponent, its suppression of +1/+1 counters applies exclusively to your opponents' creatures—allowing your own creature to slip back to the battlefield entirely clean. From there, you simply feed the creature into Thermopod for a rush of red mana, triggering the undying loop all over again.