Nether Traitor, Phantom Train, Sek'Kuar, Deathkeeper, and A Realm Reborn

Prerequisites

• Nether Traitor on the battlefield
• Phantom Train on the battlefield
• Sek'Kuar, Deathkeeper on the battlefield
• A Realm Reborn on the battlefield

Steps

1. Activate Phantom Train by sacrificing Nether Traitor Sek'Kuar triggers, creating a 3/1 Graveborn creature token creature with haste
2. Resolve the Phantom Train ability, putting a +1/+1 counter on it and causing it to become a Spirit artifact creature in addition to its other types until end of turn
3. Activate the Graveborn token using the ability granted by A Realm Reborn by tapping it, adding
4. Activate Phantom Train by sacrificing the Graveborn token Nether Traitor triggers, causing you to pay to return it from your graveyard to the battlefield
5. Resolve the Phantom Train ability, putting a +1/+1 counter on it and causing it to become a Spirit artifact creature in addition to its other types until end of turn
6. Activate Nether Traitor using the ability granted by A Realm Reborn by tapping it, adding
7. Repeat

Results

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