Animate a Forest that enters untapped using Llanowar Loamspeaker
Cast Springheart Nantuko for its bestow cost by paying {1}{G}, attaching it to the animated Forest.
Play a land. When the land enters, Springheart Nantuko triggers, causing you to pay {1}{G} to create two token copies of the Forest that enters untapped.
When the Forest tokens enter, Springheart Nantuko triggers twice.
Holding priority, activate the Forest tokens by tapping them, adding {G}{G}.
Resolve the first Springheart Nantuko trigger, choosing not to pay and creating two 1/1 Insect creature tokens.
Resolve the second Springheart Nantuko trigger, causing you to pay {1}{G} to create two token copies of the Forest that enters untapped.
Repeat from step 4.

Infinite ETB

Infinite creature tokens

Infinite landfall triggers

Infinite tapped Forest tokens

Springheart Nantuko

Llanowar Loamspeaker

Doubling Season

Animate the land that has Squirrel Nest attached using Llanowar Loamspeaker.
Activate the land with Squirrel Nest attached by tapping it, creating a 1/1 Squirrel creature token.
When the Squirrel enters, Intruder Alarm triggers, untapping all creatures.
Repeat from step 2.

Infinite mana creatures you control can produce

Infinite untap of creatures

Squirrel Nest

Intruder Alarm

Activate Llanowar Loamspeaker's second ability by tapping it, causing Grove of the Burnwillows to become a creature until end of turn.
Activate Marvin using Grove of the Burnwillows' second ability by tapping it, adding {R} or {G} and causing each opponent to lose 1 life due to Tainted Remedy.
Activate Marvin using Pili-Pala's ability by paying {2} and untapping it, adding {1}.
Repeat from step 2.

Infinite lifeloss

Grove of the Burnwillows

Pili-Pala

Marvin, Murderous Mimic

Tainted Remedy

Activate Llanowar Loamspeaker's second ability by tapping it, causing Minamo to become a 3/3 Elemental creature with haste that's still a land until end of turn.
Activate Arixmethes by tapping it, adding {G}{U}.
Activate Minamo's second ability by paying {U} and tapping it, untapping Ioreth of the Healing House.
Activate Ioreth of the Healing House's second ability by tapping it, untapping Minamo and Arixmethes.
Repeat from step 2.

Infinite green mana

Ioreth of the Healing House

Arixmethes, Slumbering Isle

Minamo, School at Water's Edge

Activate Llanowar Loamspeaker's second ability by tapping it, causing the land with Tarmogoyf Nest attached to become a creature until end of turn.
Activate any number of creatures you control by tapping them, adding at least {1}{G}.
Activate the land with Tarmogoyf Nest attached by paying {1}{G} and tapping it, creating a Tarmogoyf creature token.
When the Tarmogoyf enters the battlefield, Intruder Alarm triggers, untapping all creatures.
Repeat from step 2.

Tarmogoyf Nest

Combos with "Llanowar Loamspeaker"