Hardened Academic + Phantom Train + Putrid Goblin

RWB identity

Commander legal

The 3 combo pieces

• Hardened Academic
• Phantom Train
• Putrid Goblin

How to execute it

1. Activate Phantom Train by sacrificing Putrid Goblin.
2. When Putrid Goblin 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 Putrid Goblin.
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