Medomai the Ageless + Idris, Soul of the TARDIS + Thrummingbird + Transmogrifying Licid

Medomai the Ageless

Idris, Soul of the TARDIS

Thrummingbird

Transmogrifying Licid

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. Deal combat damage to an opponent using Idris and Thrummingbird.
8. Idris and Thrummingbird trigger.
9. Resolve the Idris trigger, causing you to take an extra turn after this one.
10. Resolve the Thrummingbird trigger, putting a time counter on Idris.
11. Repeat from step 5.

This ingenious setup bypasses Medomai the Ageless's restriction against attacking during extra turns by letting Idris, Soul of the TARDIS safely inherit Medomai's glorious combat damage trigger. To tie this mechanical marvel together, Transmogrifying Licid must first turn Medomai into an artifact before it gets exiled, allowing Idris's imprint ability to properly swallow it whole while receiving a nice size boost. Meanwhile, every time Thrummingbird swoops in for combat damage, its proliferate trigger adds a precious time counter back to Idris, staving off its vanishing decay so the infinite turns can march on indefinitely.