Idris, Soul of the TARDIS + Lithoform Engine + Basalt Monolith + Sphinx's Disciple + Thran Forge

Idris, Soul of the TARDIS

Lithoform Engine

Basalt Monolith

Sphinx's Disciple

Thran Forge

How it works

1. Activate Thran Forge by paying 2, causing Sphinx's Disciple to get +1/+0 and to become an artifact until end of turn.
2. Cast Idris either from your hand or from the command zone by paying 1 and commander tax, if applicable.
3. When Idris enters the battlefield, its imprint ability triggers, targeting Sphinx's Disciple.
4. Holding priority, activate Lithoform Engine's first ability by paying 2 and tapping it, copying Idris' trigger, targeting Basalt Monolith.
5. Resolve both Idris triggers, exiling Basalt Monolith and Sphinx's Disciple.
6. During your next turn, activate Idris using Basalt Monolith's first ability by tapping it, adding CCC.
7. Activate Idris using Basalt Monolith's second ability by paying 3, untapping it.
8. Sphinx's Disciple triggers, causing you to draw a card.
9. Repeat from step 6.

This ingenious loop hinges on Idris, Soul of the TARDIS entering the battlefield and using Lithoform Engine to double its imprint trigger, allowing it to successfully swallow both Basalt Monolith and Sphinx's Disciple at the same time. Because Idris gains all the activated and triggered abilities of the exiled cards, it can repeatedly tap for mana using the Monolith's ability and pay to untap itself, which conveniently triggers the Disciple's inspired ability to draw you a card on each untap. Naturally, this whole mechanical symphony requires Thran Forge to temporarily turn Sphinx's Disciple into an artifact so that Idris's imprint ability can target it in the first place.