Fiend Hunter, Karmic Guide, and Phantom Train

Prerequisites

• Fiend Hunter in hand
• Karmic Guide on the battlefield
• Phantom Train on the battlefield
• available

Steps

1. Cast Fiend Hunter by paying its mana cost
2. When Fiend Hunter enters, its first ability triggers, exiling Karmic Guide
3. Activate Phantom Train by sacrificing Fiend Hunter
4. When Fiend Hunter dies, its second ability triggers, returning Karmic Guide from exile to the battlefield
5. When Karmic Guide enters, it triggers, returning Fiend Hunter from your graveyard to the battlefield
6. When Fiend Hunter enters, its first ability triggers, exiling Karmic Guide
7. Resolve the Phantom Train ability
8. Repeat from step 3

Results

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