Activate Saproling Burst by removing a fade counter from it, creating a Saproling creature token.
The Saproling enters the battlefield as a 1/1 Saproling and a Forest land due to Life and Limb.
Evolution Sage triggers, putting a fade counter on Saproling Burst.
Repeat.

Infinite creature tokens

Infinite creature ETB

Infinite Forest tokens

Infinite landfall triggers

Infinite proliferate

Infinite green mana

Saproling Burst

Life and Limb

Evolution Sage

Activate Saproling Burst by removing a fade counter from it, creating a */* Saproling creature token.
When the Saproling enters the battlefield, Intruder Alarm triggers, untapping all creatures.
Activate Xavier Sal's second ability by tapping it and sacrificing the Saproling, putting a fade counter on Saproling Burst.
Repeat.

Infinite death triggers

Infinite creature LTB

Infinite mana creatures you control can produce

Infinite creature sacrifice triggers

Infinite untap of creatures

Xavier Sal, Infested Captain

Intruder Alarm

Activate Xavier Sal's second ability by tapping it and sacrificing another creature, putting a +1/+1 counter on it and a fade counter on Saproling Burst.
Activate Saproling Burst by removing a fade counter from it, creating a Saproling creature token.
Activate Xavier Sal using Devoted Druid's second ability by putting a -1/-1 counter on it, untapping Xavier Sal.
Repeat.

Agatha's Soul Cauldron

Devoted Druid

Activate Saproling Burst by removing a fade counter from it, creating a */* Saproling creature token.
When the Saproling enters the battlefield, Tainted Observer triggers.
Holding priority, activate Ashnod's Altar by sacrificing the Saproling, adding {C}{C}.
Resolve the Tainted Observer trigger, causing you to pay {2} to put a fade counter on Saproling Burst.
Repeat.

Tainted Observer

Ashnod's Altar

Activate Saproling Burst by removing a fade counter from it, creating a */* Saproling creature token.
When the Saproling enters the battlefield, Tainted Observer and Mana Echoes triggers.
Resolve the Mana Echoes trigger, adding {C} for each Saproling you control.
Resolve the Tainted Observer trigger, causing you to pay {2} to put a fade counter on Saproling Burst.
Repeat.

Infinite colorless mana

Mana Echoes

Tap Kilo by any method.
Kilo triggers, causing you to proliferate and put a fade counter on Saproling Burst.
Activate Saproling Burst by removing a fade counter from it, creating a Saproling creature token.
When the creature token enters the battlefield, Intruder Alarm triggers, untapping all creatures.
Repeat.

Cards Allowing a Creature to Tap for Free

Kilo, Apogee Mind

Combos with "Saproling Burst"