Activate The Unbeatable Squirrel Girl by paying {1}{G}{G}{G}, creating a 1/1 Squirrel creature token for each Squirrel you control.
Activate four Squirrels by tapping them, adding {1}{G}{G}{G}.
Repeat

Infinite ETB

Infinite colored mana

Infinite creature tokens with haste

The Unbeatable Squirrel Girl

Cryptolith Rite

Concordant Crossroads

Activate The Unbeatable Squirrel Girl by paying {1}{G}{G}{G}, creating a 1/1 Squirrel creature token for each Squirrel you control.
Activate Phyrexian Altar four times by sacrificing four Squirrels, adding {1}{G}{G}{G}.
Repeat.

Infinite LTB

Infinite creature tokens

Infinite death triggers

Infinite sacrifice triggers

Phyrexian Altar

Activate The Unbeatable Squirrel Girl by paying {1}{G}{G}{G}, creating a 1/1 Squirrel creature token for each Squirrel you control.
Activate Earthcraft by tapping a Squirrel, untapping a basic Forest.
Activate the Forest by tapping it, adding {G}.
Repeat steps 2 and 3 three additional times.
Repeat from step 1.

Infinite mana basic lands you control can produce

Infinite untap of basic lands you control

Earthcraft

Activate The Unbeatable Squirrel Girl by paying {1}{G}{G}{G}, creating a 1/1 Squirrel creature token for each Squirrel you control.
Activate Supportive Parents four times by tapping eight Squirrels, adding {1}{G}{G}{G}.
Repeat from step 1.

Supportive Parents

Activate The Unbeatable Squirrel Girl by paying {1}{G}{G}{G}, creating a 1/1 Squirrel creature token for each Squirrel you control.
Activate Ashnod's Altar three times by sacrificing three Squirrels, adding six {C}
When the Squirrels die, Pitiless Plunderer triggers three times, creating three Treasure tokens.
Activate three Treasures by tapping and sacrificing them, adding {G}{G}{G}.
Repeat.

Infinite Treasure tokens

Infinite colorless mana

Pitiless Plunderer

Ashnod's Altar

Activate The Unbeatable Squirrel Girl by paying {1}{G}{G}{G}, creating a 1/1 Squirrel creature token for each Squirrel you control.
Activate Baylen's first ability four times by tapping eight Squirrel tokens, adding {1}{G}{G}{G}.
Repeat.

Infinite draw triggers

Infinite +1/+1 counters on a creature

Infinite card draw

Baylen, the Haymaker

Activate Ashnod's Altar by sacrificing The Unbeatable Squirrel Girl, adding {C}{C}.
When The Unbeatable Squirrel Girl dies, Nim Deathmantle triggers, causing you to pay {4} to return The Unbeatable Squirrel Girl from your graveyard to the battlefield and attach Nim Deathmantle to it.
When The Unbeatable Squirrel Girl enters, it triggers, creating a creature token.
Activate Ashnod's Altar by sacrificing a creature token, adding {C}{C}.
Repeat.

Nim Deathmantle

Declare The Incredible Hulk and The Unbeatable Squirrel Girl as attackers.
The Unbeatable Squirrel Girl triggers, creating a creature token.
Holding priority, activate Goblin Bombardment by sacrificing a creature token, dealing 1 damage to The Incredible Hulk.
The Incredible Hulk triggers, putting a +1/+1 counter on it, then untapping it and causing you to get an additional combat phase after this one.
Repeat each combat phase.

Infinite combat phases

Bruce Banner // The Incredible Hulk

Goblin Bombardment

Activate The Unbeatable Squirrel Girl by paying {1}{G}{G}{G}, creating a 1/1 Squirrel creature token for each Squirrel you control.
Activate Seton four times by tapping four Squirrels, as they'll be Druids due to Maskwood Nexus, adding {G}{G}{G}{G}.
Repeat

Infinite green mana

Seton, Krosan Protector

Maskwood Nexus

Declare the creature with Breath of Fury attached and The Unbeatable Squirrel Girl as attackers.
The Unbeatable Squirrel Girl triggers, creating a creature token.
Deal combat damage using the creature that has Breath of Fury attached. 
Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to the creature token, then causing you to untap all creatures you control and to get an additional combat phase after this one.
Repeat each combat phase.

Combos with "The Unbeatable Squirrel Girl"