Activate all basic lands you control by tapping them, adding at least {6}{G}{G}{G}{G}{G}.
Cast Early Harvest by paying {1}{G}{G}, untapping all basic lands you control.
Activate Shigeki's channel ability by paying {4}{G}{G} and discarding it, returning Early Harvest and Regrowth from your graveyard to your hand.
Cast Regrowth by paying {1}{G}, returning Shigeki to your hand from your graveyard.
Repeat.
If basic lands you control can tap to produce at least {7}{G}{G}{G}{G}{G}, this combo nets infinite mana.

Infinite magecraft triggers

Infinite mana basic lands you control can produce

Infinite self-discard triggers

Infinite storm count

Infinite untap of basic lands you control

Return most cards from your graveyard to your hand

Shigeki, Jukai Visionary

Regrowth

Early Harvest

Cast Early Harvest targeting yourself.
Activate Temur Sabertooth to return Eternal Witness to your hand.
Cast Eternal Witness returning Early Harvest to your hand from your graveyard.
Repeat.

Infinite colored mana

Infinite ETB

Infinite LTB

Infinite blinking

Temur Sabertooth

Eternal Witness

Cast Early Harvest by paying {1}{G}{G}.
Holding priority, activate all basic lands by tapping them, adding at least {4}{R}{R}.
Cast Reiterate with buyback by paying {4}{R}{R}, copying Early Harvest and returning Reiterate to your hand.
Resolve the copy of Early Harvest, untapping all basic lands you control.
Repeat from step 2.

Reiterate

Activate all basic lands you control by tapping them, adding at least {5}{G}{G}{G}{G}{G}{U}.
Cast Early Harvest by paying {1}{G}{G}, untapping all basic lands you control.
Activate Shigeki's channel ability by paying {4}{G}{G} and discarding it, returning Early Harvest and Auroral Procession from your graveyard to your hand.
Cast Auroral Procession by paying {G}{U}, returning Shigeki to your hand from your graveyard.
Repeat.

Auroral Procession

Cast Borne Upon a Wind by paying {1}{U}, allowing you to cast spells as though they have flash this turn.
Activate any number of basic lands by tapping them, adding at least {3}{U}{R}.
Cast Early Harvest by paying {1}{G}{G}.
Holding priority, activate Rootha by paying {2} and returning it from the battlefield to your hand, copying Early Harvest
Resolve the Early Harvest copy, untapping all basic lands you control.
Activate any number of basic lands by tapping them, adding at least {3}{U}{R}.
Cast Rootha by paying {1}{U}{R}.
Repeat from step 4.

Rootha, Mercurial Artist

Borne Upon a Wind

Activate any number of basic lands by tapping them, adding at least {2}{G}{U}{R}.
Cast Early Harvest by paying {1}{G}{G}.
Holding priority, activate Rootha by paying {2} and returning it from the battlefield to your hand, copying Early Harvest.
Resolve the copy of Early Harvest, untapping all basic lands you control.
Activate any number of basic lands by tapping them, adding at least {2}{G}{U}{R}.
Resolve Early Harvest, untapping all basic lands you control.
Cast Rootha by paying {1}{U}{R}.
Cast Lore Drakkis for its mutate cost by paying {U/R}{U/R}, mutating it on top of Rootha.
When Lore Drakkis enters the battlefield, it triggers, returning Early Harvest from your graveyard to your hand.
Repeat.

Infinite recursion of instant and sorcery cards from your graveyard

Lore Drakkis

Cast Early Harvest by paying its mana cost, untapping at least five basic lands.
Cast a copy of Regrowth from exile by paying {1}{G}, targeting Early Harvest.
Spellweaver Helix's last ability triggers, allowing you to cast the Extra Combat Sorcery, giving you an additional combat phase and an additional main phase this turn.
Resolve the copy of Regrowth, returning Early Harvest from your graveyard to your hand.
Declare Emeritus of Abundance as an attacker.
When Emeritus of Abundance attacks, it triggers, becoming prepared.
Repeat each main phase.

Infinite combat phases

Extra Combat Sorcery

Spellweaver Helix

Emeritus of Abundance // Regrowth

Cast a copy of Regrowth from exile by paying {1}{G}, targeting any card besides the actual Regrowth.
Pyromancer's Ascension's first ability triggers, allowing you to put a quest counter on it.
Resolve the copy of Regrowth, returning that card from your graveyard to your hand.
Declare Emeritus of Abundance as an attacker.
When Emeritus of Abundance attacks, it triggers, becoming prepared.
During your second main phase, cast a copy of Regrowth by paying {1}{G}, targeting the actual Regrowth card.
Pyromancer Ascension's first ability triggers, allowing you to put a quest counter on it.
Resolve the copy of Regrowth, returning Regrowth from your graveyard to your hand.
Cast Early Harvest by paying its mana cost.
Pyromancer Ascension's second ability triggers, copying Early Harvest.
Resolve a copy of Early Harvest, untapping basic lands you control.
Activate those lands by tapping them, adding mana.
Resolve the remaining copy of Early Harvest, untapping lands you control.
Activate those lands by tapping them, adding mana.
Activate Ashnod's Altar by sacrificing Emeritus of Abundance, producing that card's result.
Cast the card Regrowth from your hand by paying {1}{G}, targeting Emeritus of Abundance.
Pyromancer Ascension's second ability triggers, copying Regrowth and allowing you to target Early Harvest with the copy.
Resolve both copies of Regrowth, returning Emeritus of Abundance and Early Harvest from your graveyard to your hand.
Cast Early Harvest by paying its mana cost.
Pyromancer Ascension's second ability triggers, copying Early Harvest.
Resolve a copy of Early Harvest, untapping lands you control.
Activate those lands by tapping them, adding mana.
Resolve the remaining copy of Early Harvest, untapping lands you control.
Activate those lands by tapping them, adding mana.
Cast Emeritus of Abundance by paying {2}{G}.
Cast a copy of Regrowth from exile by paying {1}{G}, targeting Early Harvest.
Both of Pyromancer Ascension's abilities trigger.
In response, activate Ashnod's Altar by sacrificing Emeritus of Ideation, producing that card's result.
Resolve Pyromancer Ascension's first abiliity, putting a redundant quest counter on it if desired.
Resolve Pyromancer Ascension's second ability, copying Regrowth and targeting Emeritus of Abundance with the copy.
Repeat from step 18.

Combos with "Early Harvest"