Xu-Ifit, Osteoharmonist, Thornbite Staff, and Phantom Train

Prerequisites

• Xu-Ifit, Osteoharmonist on the battlefield
• Thornbite Staff on the battlefield
• Phantom Train on the battlefield

Steps

1. Activate Xu-Ifit by tapping it, returning a creature card from your graveyard to the battlefield
2. Activate Phantom Train by sacrificing the creature returned in step 1
3. When the creature dies, Xu-Ifit triggers, untapping itself
4. Resolve the Phantom Train ability
5. Repeat

Results

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