Hardened Academic + Phantom Train + Restless Apparition

RWB identity

Commander legal

The 3 combo pieces

• Hardened Academic
• Phantom Train
• Restless Apparition

How to execute it

1. Activate Phantom Train by sacrificing Restless Apparition.
2. When Restless Apparition dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Hardened Academic triggers, putting a +1/+1 counter on Restless Apparition.
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