Medomai the Ageless + Idris, Soul of the TARDIS + Karn's Bastion + Encroaching Mycosynth

Medomai the Ageless

Idris, Soul of the TARDIS

Karn's Bastion

Encroaching Mycosynth

How it works

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. Cast Idris by paying 1.
4. When Idris enters the battlefield, it triggers, exiling Medomai the Ageless until Idris leaves the battlefield.
5. Move to your extra turn.
6. At the beginning of your upkeep, Idris's vanishing ability triggers, removing a time counter from it.
7. Activate Karn's Bastion's second ability by paying 4 and tapping it, putting a time counter on Idris.
8. Deal combat damage to an opponent using Idris.
9. Idris triggers, causing you to take an extra turn after this one.
10. Repeat from step 5.

By turning every nonland permanent into an artifact with Encroaching Mycosynth, we set the stage for Idris, Soul of the TARDIS to imprint the legendary Medomai the Ageless upon entering the battlefield. Normally bound by the Sphinx's restriction against attacking during extra turns, Idris cleanly bypasses this curse by copying its activated and triggered abilities without inheriting its text box limitations. To prevent Idris from fading away to its native Vanishing 3, Karn's Bastion steps in to constantly replenish its time counters through proliferation. The result is an unstoppable loop where Idris seamlessly steps into Medomai's shoes, granting you infinite consecutive turns to safely lock down the game.