Tromell, Seymour's Butler, and Phantom Train

Prerequisites

• Tromell, Seymour's Butler on the battlefield
• Phantom Train on the battlefield

Steps

1. Activate Phantom Train by sacrificing the persist creature
2. When the persist creature dies, its persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to Tromell Resolve the Phantom Train ability
3. Repeat

Results

• Infinite +1/+1 counters on a creature
• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers