Blasting Station, Twilight Shepherd, and Hardened Academic

Prerequisites

• Blasting Station on the battlefield
• Twilight Shepherd on the battlefield
• Hardened Academic on the battlefield

Steps

1. Activate Blasting Station by tapping it and sacrificing Twilight Shepherd
2. When Twilight Shepherd dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. Hardened Academic and Blasting Station trigger
4. Resolve the Hardened Academic trigger, putting a +1/+1 counter on Twilight Shepherd
5. Resolve the Blasting Station trigger, untapping it
6. Resolve the Blasting Station ability from step 1
7. Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite damage
• Infinite death triggers
• Infinite sacrifice triggers