Stalwart Successor, Puppeteer Clique, and Phantom Train

Prerequisites

• Stalwart Successor on the battlefield
• Puppeteer Clique on the battlefield
• Phantom Train on the battlefield

Steps

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

Results

• Infinite +1/+1 counters on a creature
• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers
• Put all creature cards from each opponent's graveyard onto the battlefield under your control