Puppeteer Clique, Umbral Collar Zealot, and Hardened Academic

Prerequisites

• Puppeteer Clique on the battlefield
• Umbral Collar Zealot on the battlefield
• Hardened Academic on the battlefield

Steps

1. Activate Umbral Collar Zealot 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. Hardened Academic and Puppeteer Clique trigger
4. Resolve the Hardened Academic trigger, putting a +1/+1 counter on Puppeteer Clique
5. Resolve the Puppeteer Clique trigger, allowing you to put a creature card from an opponent's graveyard onto the battlefield under your control
6. Resolve the Umbral Collar Zealot ability Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers
• Infinite surveil
• Put all creature cards from each opponent's graveyard onto the battlefield under your control