Stalwart Successor + Viscera Seer + Puppeteer Clique

Stalwart Successor

Viscera Seer

Puppeteer Clique

How it works

1. Activate Viscera Seer by sacrificing Puppeteer Clique
2. When Puppeteer Clique dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Puppeteer Clique enters, it and Stalwart Successor trigger.
4. Resolve the Puppeteer Clique trigger, putting a creature from an opponent's graveyard onto the battlefield under your control.
5. Resolve the Stalwart Successor trigger, putting a +1/+1 counter on Puppeteer Clique
6. Resolve the Viscera Seer ability.
7. Repeat.

This infinite loop hinges on the clever interaction between Puppeteer Clique's persist ability and Stalwart Successor's triggered ability. When Puppeteer Clique enters the battlefield, it receives a -1/-1 counter from persist, which instantly triggers Stalwart Successor to place a +1/+1 counter on it; because these two counters annihilate each other as a state-based action, the Clique is left with no counters at all, resetting its persist for the next cycle. You then use Viscera Seer to sacrifice the Clique—along with any creature you've stolen from an opponent's graveyard via Puppeteer Clique's enter-the-battlefield trigger—looping the process to repeatedly strip opposing graveyards while generating infinite deaths and scries.