Medomai the Ageless, Idris, Soul of the TARDIS, Sword of Truth and Justice, and Memnarch

Prerequisites

• Medomai the Ageless on the battlefield
• Idris, Soul of the TARDIS in hand
• Sword of Truth and Justice on the battlefield
• Memnarch on the battlefield
• An opponent cannot block creatures you control
• available

Steps

1. Deal combat damage to an opponent using Medomai the Ageless
2. Medomai the Ageless triggers, causing you to take an extra turn after this one
3. Activate Memnarch by paying , causing Medomai the Ageless to become an artifact
4. Cast Idris by paying
5. When Idris enters the battlefield, it triggers, exiling Medomai the Ageless until Idris leaves the battlefield
6. Activate Sword of Truth and Justice's equip ability by paying , attaching it to Idris
7. Move to your extra turn
8. At the beginning of your upkeep, Idris's vanishing ability triggers, removing a time counter from it
9. Deal combat damage to an opponent using Idris
10. Idris and Sword of Truth and Justice trigger
11. Resolve the Idris trigger, causing you to take an extra turn after this one
12. Resolve the Sword of Truth and Justice trigger, putting a +1/+1 counter on a creature you control, then putting a time counter on Idris
13. Repeat from step 7

Results

• Infinite turns