Prototype Portal, Coretapper, and Magistrate's Scepter

Prerequisites

• Prototype Portal on the battlefield
• Coretapper in exile
• Magistrate's Scepter on the battlefield
• Magistrate's Scepter has at least three charge counters
• each turn available

Steps

1. Activate Magistrate's Scepter by tapping and removing three charge counters from it, taking an extra turn after this one
2. Activate Prototype Portal by paying and tapping it, creating a copy of Coretapper
3. Move to your next turn
4. Activate Coretapper's first ability by tapping it, putting a charge counter on Magistrate's Scepter
5. Activate Coretapper's second ability by sacrificing it, putting two charge counters on Magistrate's Scepter
6. Repeat

Results

• Infinite turns