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

4-card combo · URW

Verdict

Yes — this 4-card loop chains infinite extra turns by keeping Idris, Soul of the TARDIS alive with Karn's Bastion while Medomai the Ageless waits in exile as a reset button.

Cards required: 4
Cheapest stack total: $3.48
Color identity: URW
Popularity: 0 decks
Format: Commander

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Ashnod's Transmogrant converts Medomai the Ageless into an artifact creature so Idris can exile it on entry, then Idris swings for its own extra turn each loop. Karn's Bastion's proliferate ability replaces the time counter Idris loses at upkeep, keeping it on the battlefield indefinitely — without that activation for 4 mana each turn, Idris blinks out and the loop collapses. The whole line runs in Jeskai, where Medomai is already a natural commander slot.

Recipe

How it works

Prerequisites

An opponent cannot block creatures you control.

Steps

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

Result

Infinite turns; Lock

Variations

Cheaper, tighter, alternate lines

Strionic Resonator can copy Medomai the Ageless's combat damage trigger to frontload extra turns before Idris enters, giving a safety net if Karn's Bastion is destroyed mid-loop. Deepglow Skate is a one-shot alternative to refuel Idris's time counters if the Bastion is answered — it doesn't sustain the loop on its own, but buys another rotation. The combo also requires a way to make blockers irrelevant every turn, so pair it with Vorrac Battlehorns, Whispersilk Cloak, or consistent removal to keep the attack lane clear.