Phantom Train, Dualcaster Mage, and Persist

Prerequisites

• Phantom Train on the battlefield
• Dualcaster Mage in hand
• Persist in hand
• available

Steps

1. Cast Persist by paying its mana cost, targeting any applicable target
2. Holding priority, cast Dualcaster Mage by paying its mana cost
3. When Dualcaster Mage enters, it triggers, targeting Persist
4. Holding priority, activate Phantom Train by sacrificing Dualcaster Mage
5. Resolve the Dualcaster Mage trigger, copying Persist, with the copy targeting Dualcaster Mage Resolve the Persist copy, returning Dualcaster Mage from your graveyard to the battlefield
6. Repeat from step 3

Results

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