Activate Spark Double using Avatar Kuruk's ability by paying {20} minus {1} for each creature and/or artifact you can tap while activating it, causing you to take an extra turn after this one.
Activate Baboon Spirit by paying {3}{U}, exiling Spark Double
At the beginning of your end step, Baboon Spirit triggers, returning Spark Double from exile to the battlefield. Choose to have it enter the battlefield as a copy of Avatar Kuruk.
Repeat each turn.

Infinite turns

The Legend of Kuruk // Avatar Kuruk

Baboon Spirit

Spark Double

Activate Avatar Kuruk by paying {20} minus {1} for each creature and/or artifact you can tap while activating it, causing you to take an extra turn after this one.
Activate Baboon Spirit by paying {3}{U}, exiling Avatar Kuruk.
At the beginning of your end step, Baboon Spirit triggers, returning The Legend of Kuruk from exile to the battlefield with a lore counter on it.
The Legend of Kuruk's first chapter ability triggers, causing you to scry 2 and draw a card.
Move to your next turn. At the beginning of your precombat main phase. The Legend of Kuruk triggers, putting a lore counter on it. Its second chapter ability then triggers, causing you to scry 2 and draw a card.
Activate Karn's Bastion by paying {4} and tapping it, causing you to proliferate and put a lore counter on The Legend of Kuruk.
The Legend of Kuruk's third chapter ability triggers, causing you to exile it and return it to the battlefield as Avatar Kuruk.
Repeat.

Karn's Bastion

Activate Avatar Kuruk by paying {20} minus {1} for each creature and/or artifact you can tap while activating it, causing you to take an extra turn after this one.
At the beginning of your end step, Baboon Spirit triggers, blinking Avatar Kuruk and causing it to return to the battlefield as The Legend of Kuruk with two lore counters on it due to Doubling Season.
The Legend of Kuruk's first and second chapter abilities trigger, causing you to scry 2, draw a card, scry 2 and draw another card.
Move to your next turn. At the beginning of your precombat main phase. The Legend of Kuruk triggers, putting two lore counters on it. Its third chapter ability triggers, causing you to exile it and return it to the battlefield as Avatar Kuruk.
Repeat.

Doubling Season

Activate Marvin using Avatar Kuruk's ability by paying {20} minus {1} for each creature and/or artifact you can tap while activating it, causing you to take an extra turn after this one.
Activate Baboon Spirit by paying {3}{U}, exiling Marvin.
At the beginning of your end step, Baboon Spirit triggers, returning Marvin from exile to the battlefield
Repeat each turn.

Marvin, Murderous Mimic

Cast Illusion of Choice by paying {U}, allowing you to decide how each player votes this turn and causing you to draw a a card.
Cast Plea for Power by paying {3}{U}, choosing all votes to be for time, causing you to take an extra turn after this one.
Activate Baboon Spirit by paying {3}{U}, exiling Scholar of the Ages.
At the beginning of your end step, Baboon Spirit triggers, returning Scholar of the Ages from exile to the battlefield.
When Scholar of the Ages enters the battlefield, it triggers, returning Illusion of Choice and Plea for Power from your graveyard to your hand.
Repeat each turn.

Plea for Power

Illusion of Choice

Scholar of the Ages

Activate Avatar Kuruk by paying {20} minus {1} for each creature and/or artifact you can tap while activating it, causing you to take an extra turn after this one.
At the beginning of your end step, Baboon Spirit triggers, blinking Avatar Kuruk and causing it to return to the battlefield as The Legend of Kuruk. Choose to have it enter with three lore counters due to its read-ahead ability given to it by Barbara Wright.
The Legend of Kuruk's third chapter ability triggers, causing you to exile it and return it to the battlefield as Avatar Kuruk.
Repeat.

Barbara Wright

Activate Timestream Navigator by paying {2}{U}{U}, tapping and putting it on the bottom of your library, causing you to take an extra turn after this one.
Activate Baboon Spirit by paying {3}{U}, exiling Wormfang Manta
At the beginning of your end step, Baboon Spirit triggers, returning Wormfang Manta from exile to the battlefield.
Forerunner of the Coalition enters, triggering its first ability, causing you to search your library for Timestream Navigator and put it on top of your library.
Move to your next turn, drawing Timestream Navigator during your draw phase.
Cast Timestream Navigator by paying {1}{U}.
Timestream Navigator enters the battlefield, triggering Forerunner of the Coalition's second ability, causing each opponent to lose 1 life.
Repeat.

Forerunner of the Coalition

Timestream Navigator

Cast Exchange of Words by paying {1}{U}{U}.
When Exchange of Words enters the battlefield, it triggers, exchanging the text boxes of it and Wormfang Manta.
Activate Baboon Spirit by paying {3}{U}, exiling Wormfang Manta
At the beginning of your end step, Baboon Spirit triggers, returning Wormfang Manta from exile to the battlefield.
Exchange of Words leaves and enters the battlefield, triggering the second ability it gained from Wormfang Manta's textbox as well as its own ability.
Resolve the first Exchange of Words trigger, causing you to take an extra turn after this one.
Resolve the second Exchange of Words trigger, exchanging the text boxes of it and Wormfang Manta.
Repeat from step 3 during each turn.

Exchange of Words

Starfield of Nyx

Wormfang Manta

Opalescence

Activate Coretapper's first ability by tapping it, putting a charge counter on Magistrate's Scepter.
Activate Coretapper's second ability by sacrificing it, putting two charge counters on Magistrate's Scepter.
Activate Magistrate's Scepter's second ability by tapping it and removing three charge counters from it, causing you to take an extra turn after this one.
Activate Baboon Spirit by paying {3}{U}, exiling Sharuum.
At the beginning of your end step, Baboon Spirit triggers, returning Sharuum from exile to the battlefield.
When Sharuum enters the battlefield, it triggers, returning Coretapper from your graveyard to the battlefield.
Repeat each turn.

Sharuum the Hegemon

Coretapper

Magistrate's Scepter

At the beginning of your upkeep, Panoptic Mirror triggers, casting a copy of Moonmist without paying its mana cost.
Resolve Moonmist, transforming Ultimecia, Time Sorceress into Ultimecia, Omnipotent.
Ultimecia, Omnipotent triggers, causing you to take an extra turn after this one.
Activate Baboon Spirit by paying {3}{U}, exiling Infinite Guideline Station.
At the beginning of your end step, Baboon Spirit triggers, returning Ultimecia, Time Sorceress from exile to the battlefield.
Whenever Ultimecia, Time Sorceress enters the battlefield, it triggers, causing you to surveil 2.
Repeat each turn.

Ultimecia, Time Sorceress // Ultimecia, Omnipotent

Moonmist

Panoptic Mirror

Activate Isochron Scepter by paying {2} and tapping it, casting a copy of Moonmist without paying its mana cost.
Resolve Moonmist, transforming Ultimecia, Time Sorceress into Ultimecia, Omnipotent.
Ultimecia, Omnipotent triggers, causing you to take an extra turn after this one.
Activate Baboon Spirit by paying {3}{U}, exiling Infinite Guideline Station.
At the beginning of your end step, Baboon Spirit triggers, returning Ultimecia, Time Sorceress from exile to the battlefield.
Whenever Ultimecia, Time Sorceress enters the battlefield, it triggers, causing you to surveil 2.
Repeat each turn.

Isochron Scepter

Cast Infinite Guideline Station either from your hand or from the command zone by paying {W}{U}{B}{R}{G} plus commander tax if applicable.
When Infinite Guideline Station enters, it triggers, creating a 2/2 Robot artifact creature token for each multicolored permanent you control.
Activate Infinite Guideline Station's station ability by tapping any number of creatures with total power 12 or greater, putting at least twelve charge counters on Infinite Guideline Station, causing it to become a creature.
Activate Time Sieve by tapping it and sacrificing five Robots, causing you to take an extra turn after this one.
Activate Baboon Spirit by paying {3}{U}, exiling Infinite Guideline Station.
At the beginning of your end step, Baboon Spirit triggers, returning Infinite Guideline Station from exile to the battlefield.
When Infinite Guideline Station enters, it triggers, creating a 2/2 Robot artifact creature token for each multicolored permanent you control.
Repeat from step 3 each turn.

Combos with "Baboon Spirit"