Metamorphosis Fanatic, Prowling Geistcatcher, and Phantom Train

Prerequisites

• Metamorphosis Fanatic on the battlefield
• Prowling Geistcatcher on the battlefield
• Phantom Train on the battlefield

Steps

1. Activate Phantom Train by sacrificing Metamorphosis Fanatic
2. When Metamorphosis Fanatic dies, Prowling Geistcatcher's first ability triggers, exiling Metamorphosis Fanatic from your graveyard
3. Resolve the Phantom Train ability
4. Activate Phantom Train by sacrificing Prowling Geistcatcher
5. When Prowling Geistcatcher dies, its second ability triggers, returning Metamorphosis Fanatic from exile to the battlefield
6. When Metamorphosis Fanatic enters the battlefield, it triggers, returning Prowling Geistcatcher from your graveyard to the battlefield
7. Resolve the Phantom Train ability
8. Repeat

Results

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