Athreos, Shroud-Veiled, Blue, Loyal Raptor, and Phantom Train

Prerequisites

• Athreos, Shroud-Veiled on the battlefield
• Blue, Loyal Raptor on the battlefield
• Phantom Train on the battlefield

Steps

1. Cast the Dinosaur in your hand by paying its mana cost
2. It will enter with a coin counter due to Blue
3. Activate Phantom Train by sacrificing the Dinosaur
4. When the Dinosaur dies, Athreos's second ability triggers, returning the Dinosaur from your graveyard to the battlefield
5. It will enter with a coin counter due to Blue
6. Resolve the Phantom Train ability
7. Repeat from step 2

Results

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