Meren of Clan Nel Toth, Coretapper, and Magistrate's Scepter

Prerequisites

• Meren of Clan Nel Toth on the battlefield
• Coretapper on the battlefield
• Magistrate's Scepter on the battlefield
• You have at least one experience counter
• Coretapper does not have summoning sickness

Steps

1. Activate Coretapper's first ability by tapping it, putting a charge counter on Magistrate's Scepter
2. Activate Coretapper's second ability by sacrificing it
3. Meren's first ability triggers, giving you an experience counter
4. Resolve Coretapper's ability, putting two additional charge counters on Magistrate's Scepter
5. Activate Magistrate's Scepter's second ability by tapping it and removing three charge counters from it, causing you to take an extra turn after this one
6. At the beginning of your end step, Meren's second ability triggers, returning Coretapper from your graveyard to the battlefield
7. Repeat each turn

Results

• Infinite turns