Gravelgill Axeshark + Phantom Train + Thran Vigil

UB identity

Commander legal

The 3 combo pieces

• Gravelgill Axeshark
• Phantom Train
• Thran Vigil

How to execute it

1. Activate Phantom Train by sacrificing Gravelgill Axeshark.
2. When Gravelgill Axeshark dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Thran Vigil triggers, putting a +1/+1 counter on Gravelgill Axeshark.
4. Resolve the Phantom Train ability.
5. Repeat.

What the combo produces

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