Play Karoo.
When Karoo enters, it and Retreat to Emeria trigger.
Resolve the Retreat to Emeria trigger, creating a 1/1 Kor Ally creature token.
When the Kor Ally enters, Haru triggers, earthbending Karoo.
Resolve the Karoo trigger from step 2, causing you to sacrifice it
Haru triggers, returning Karoo from your graveyard to the battlefield.
Repeat from step 2.

Infinite ETB

Infinite lifegain triggers

Infinite lifegain

Infinite creature tokens

Infinite landfall triggers

Retreat to Emeria

Haru, Hidden Talent

Karoo

Activate Karoo by tapping it, adding {1}{W}
Activate Deserted Temple's second ability by paying {1} and tapping it, targeting itself.
Locus of Enlightenment triggers, copying Deserted Temple's ability, targeting Karoo.
Resolve both Deserted Temple abilities, untapping it and Karoo.
Repeat.

Infinite mana lands you control can produce

Infinite colorless mana

Infinite white mana

Infinite untap of lands you control

The Enigma Jewel // Locus of Enlightenment

Deserted Temple

Activate Karoo and another land by tapping them, adding at least {2}{U}.
Cast Frantic Search by paying {2}{U}.
Kitsa's prowess ability triggers, giving it +1/+1 until end of turn.
Holding priority, activate Kitsa's second ability by paying {2} and tapping it, copying Frantic Search.
Resolve the copy of Frantic Search, causing you to loot twice and untap Minamo, Karoo and another land.
Activate Karoo and another land by tapping them, adding at least {2}{U}.
Activate Minamo's second ability by paying {U} and tapping it, untapping Kitsa.
Repeat from step 4.

Infinite self-discard triggers

Infinite draw triggers

Infinite looting

Near-infinite magecraft triggers

Frantic Search

Kitsa, Otterball Elite

Minamo, School at Water's Edge

Activate Karoo by tapping it, adding {C}{W}.
Cast Kor Skyfisher by paying its mana cost.
When Kor Skyfisher enters as a land due to Ashaya, it and Stone-Seeder Hierophant trigger.
Resolve the Kor Skyfisher trigger, returning it from your graveyard to the battlefield.
Resolve the Stone-Seeder Hierophant trigger, untapping it.
Activate Stone-Seeder Hierophant by tapping it, untapping Karoo.
Repeat.

Infinite LTB

Infinite storm count

Infinite mana creatures you control can produce

Infinite untap of creatures you control

Ashaya, Soul of the Wild

Stone-Seeder Hierophant

Kor Skyfisher

Activate Karoo by tapping it, adding two mana.
Wild Growth and Vorinclex's first ability trigger, adding two additional mana.
Activate Deserted Temple's second ability by paying {1} and tapping it, targeting itself.
Rings of Brighthearth triggers, allowing you to pay {2} to copy Deserted Temple's ability, with the copy targeting Karoo.
Resolve both Deserted Temple abilities, untapping it and Karoo.
Repeat.

Vorinclex, Voice of Hunger

Rings of Brighthearth

Wild Growth

Activate Karoo by tapping it, adding two mana.
Activate Silvanus's Invoker by paying {1}, untapping Karoo and causing it to become an 8/8 Elemental with trample and haste in addition to its other types until end of turn.
Repeat any number of times.
Once you have infinite mana, you may tap and untap any other land(s) you control, and if you control lands that can produce {R} and {G}, use the mana to activate Agatha of the Vile Cauldron's ability.

Infinite power and toughness for most creatures you control until end of turn

Silvanus's Invoker

Agatha of the Vile Cauldron

Activate Lotus Field by tapping it, adding {U}{U}{U}.
Activate Karoo by tapping it, adding {C}{W}.
Activate Trazyn by paying {3} and tapping it, untapping Minamo, Lotus Field and Karoo.
Activate Minamo's second ability by paying {U}, untapping Trazyn.
Repeat from step 3.

Infinite colored mana

Candelabra of Tawnos

Trazyn the Infinite

Lotus Field

Combos with "Karoo"