Cast Quirion Sentinel for {G}, triggering Retreat to Emeria and Cloudstone Curio.
Quirion Sentinel triggers, adding {G}.
Resolve Cloudstone Curio's trigger choosing not to return another permanent.
Resolve Retreat to Emeria's trigger, creating a 1/1 Kor Ally creature token.
The Kor Ally token triggers Cloudstone Curio.
Resolve Cloudstone Curio's trigger returning Quirion Sentinel to your hand.
Repeat.

Infinite creature tokens

Infinite creature ETB

Infinite landfall triggers

Infinite creature LTB

Infinite storm count

Hamza, Guardian of Arashin

Ashaya, Soul of the Wild

Retreat to Emeria

Quirion Sentinel

Cloudstone Curio

Cast Quirion Sentinel for {G}, triggering Rampaging Baloths and Cloudstone Curio.
Quirion Sentinel triggers, adding {G}.
Resolve Cloudstone Curio's trigger choosing not to return another permanent.
Resolve Rampaging Baloths's trigger, creating a 4/4 Beast creature token.
The Beast token triggers Cloudstone Curio.
Resolve Cloudstone Curio's trigger returning Quirion Sentinel to your hand.
Repeat.

Rampaging Baloths

Cast Quirion Sentinel for {G}, triggering Felidar Retreat and Cloudstone Curio.
Quirion Sentinel triggers, adding {G}.
Resolve Cloudstone Curio's trigger choosing not to return another permanent.
Resolve Felidar Retreat's trigger, creating a 2/2 Cat Beast creature token.
The Cat Beast token triggers Cloudstone Curio.
Resolve Cloudstone Curio's trigger returning Quirion Sentinel to your hand.
Repeat.

Felidar Retreat

Cast Quirion Sentinel for {G}, triggering Sporemound and Cloudstone Curio.
Quirion Sentinel triggers, adding {G}.
Resolve Cloudstone Curio's trigger choosing not to return another permanent.
Resolve Sporemound's trigger, creating a 1/1 Saproling creature token.
The Saproling token triggers Cloudstone Curio.
Resolve Cloudstone Curio's trigger returning Quirion Sentinel to your hand.
Repeat.

Sporemound

Cast Quirion Sentinel for {G}, triggering Emeria Angel and Cloudstone Curio.
Quirion Sentinel triggers, adding {G}.
Resolve Cloudstone Curio's trigger choosing not to return another permanent.
Resolve Emeria Angel's trigger, creating a 1/1 Bird creature token with flying.
The Bird token triggers Cloudstone Curio.
Resolve Cloudstone Curio's trigger returning Quirion Sentinel to your hand.
Repeat.

Emeria Angel

Activate Kiki-Jiki by tapping it, creating a token copy of Quirion Sentinel with haste.
Quirion Sentinel enters the battlefield, adding {U}.
Activate Pemmin's Aura's first ability by paying {U}, untapping Kiki-Jiki.
Repeat.

Infinite creature tokens with haste

Kiki-Jiki, Mirror Breaker

Pemmin's Aura

Activate Kiki-Jiki by tapping it, creating a token copy of Quirion Sentinel with haste.
Quirion Sentinel enters the battlefield, adding {U}.
Activate Freed from the Real's second ability by paying {U}, untapping Kiki-Jiki.
Repeat.

Combos with "Quirion Sentinel"