Activate Lightning Greaves's equip ability by paying {0}, targeting Cephalid Illusionist.
Cephalid Illusionist triggers, causing you to mill three cards.
Resolve the Lightning Greaves ability, attaching it to Cephalid Illusionist.
Repeat.

Infinite self-mill

Cephalid Illusionist

Lightning Greaves

Activate Nomads en-Kor by paying {0}, targeting Cephalid Illusionist.
Cephalid Illusionist triggers, causing you to mill three cards.
Resolve the Nomads en-Kor ability.
Repeat.

Nomads en-Kor

Activate Lightning Greaves by paying {0}, attaching it to Cephalid Illusionist.
Cephalid Illusionist triggers, causing you to mill three cards.
Whenever a permanent card is put into your graveyard, exile it with a croak counter.
Activate Lightning Greaves by paying {0}, attaching it to Grolnok.
Repeat step 1 through 4 until your devotion to blue is greater than or equal to the number of cards in your library.
Cast Thassa's Oracle from exile by paying {U}{U}.
Thassa's Oracle enters the battlefield, winning you the game.

Win the game

Grolnok, the Omnivore

Thassa's Oracle

Activate Nomads en-Kor, targeting Cephalid Illusionist.
Mill 3.
Repeat this process until you mill your entire library.
When you mill Narcomoeba, put it on the battlefield.
Flashback Dread Return, sacrificing Nomads en-Kor, Cephalid Illusionist, and Narcomoeba, targeting Thassa's Oracle.
Resolve Thassa's Oracle's trigger with no cards in your library.

Narcomoeba

Dread Return

Declare Cephalid Illusionist as an attacker.
Holding priority, activate Reconnaissance by paying {0}, targeting Cephalid Illusionist.
Cephalid Illusionist triggers, causing you to mill three cards.
Repeat from step 2.
Resolve all Reconnaissance abilities.

Reconnaissance

Activate Chrome Mox's equip ability by paying {0}, targeting Cephalid Illusionist.
Cephalid Illusionist triggers, causing you to mill three cards.
Resolve the Chrome Mox ability, attaching it to Cephalid Illusionist.
Repeat.

Bludgeon Brawl

Chrome Mox

Activate Seat of the Synod's equip ability by paying {0}, targeting Cephalid Illusionist.
Cephalid Illusionist triggers, causing you to mill three cards.
Resolve the Seat of the Synod ability, attaching it to Cephalid Illusionist.
Repeat.

Seat of the Synod

Activate Great Furnace's equip ability by paying {0}, targeting Cephalid Illusionist.
Cephalid Illusionist triggers, causing you to mill three cards.
Resolve the Great Furnace ability, attaching it to Cephalid Illusionist.
Repeat.

Great Furnace

Activate Darksteel Citadel's equip ability by paying {0}, targeting Cephalid Illusionist.
Cephalid Illusionist triggers, causing you to mill three cards.
Resolve the Darksteel Citadel ability, attaching it to Cephalid Illusionist.
Repeat.

Darksteel Citadel

Cast Idris either from your hand or from the command zone by paying {1}{U}{R} plus commander tax, if applicable.
When Idris enters the battlefield, it triggers, exiling Psychic Battle until Idris leaves the battlefield.
Choose any number of targets by any method.
Idris triggers, causing each player to reveal the top card of their library and changing the target(s) of the spell or ability to Cephalid Illusionist.
Cephalid Illusionist and Idris trigger.
Resolve the Cephalid Illusionist trigger, causing you to mill three cards.
Resolve the Idris trigger, causing each player to reveal the top card of their library and changing the target(s) of the spell or ability to any other target.
Repeat from step 4.

Combos with "Cephalid Illusionist"