Medomai the Ageless + Idris, Soul of the TARDIS + Karn's Bastion + Ashnod's Transmogrant

Medomai the Ageless

Idris, Soul of the TARDIS

Karn's Bastion

Ashnod's Transmogrant

How it works

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

This fascinating sequence bypasses Medomai the Ageless's restriction against attacking during extra turns by letting Idris, Soul of the TARDIS step into the spotlight. By using Ashnod's Transmogrant to turn Medomai into an artifact creature, you enable Idris's imprint ability to safely exile Medomai upon entry, granting Idris both its flying keyword and its coveted combat damage trigger. To prevent Idris from fading away via its vanishing ability, Karn's Bastion steps in to constantly proliferate time counters back onto it. As long as you keep replenishing those counters, your newly minted mechanical sphinx will repeatedly secure infinite extra turns.