Prosper, Tome-Bound, Goldspan Dragon, Flameskull, Phantom Train, and Elspeth, Storm Slayer

Prerequisites

• Prosper, Tome-Bound on the battlefield
• Goldspan Dragon on the battlefield
• Flameskull on the battlefield or in exile
• Phantom Train on the battlefield
• Elspeth, Storm Slayer on the battlefield
• available

Steps

1. Activate Phantom Train by sacrificing Flameskull
2. When Flameskull dies, it triggers, exiling it and the top card of your library with the ability to cast one from exile this turn
3. Resolve the Phantom Train ability
4. Cast Flameskull from exile by paying
5. Prosper's second ability triggers, creating two Treasure tokens
6. Activate the Treasures by tapping and sacrificing them, adding
7. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite colored mana
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite storm count
• Exile your library
• Infinite Treasure tokens
• Infinite +1/+1 counters on a creature