Activate Emiel the Blessed by paying {3}, blinking Felothar.
When Felothar enters the battlefield, it triggers, causing you to sacrifice a nonland permanent and put a +1/+1 counter on each creature you control.
Basking Broodscale triggers, creating a creature token.
Activate Crystalline Crawler by removing a +1/+1 counter from it, adding {1}.
Activate Cryptic Trilobite by removing a +1/+1 counter from it, adding {C}{C} that can only be spent to activate abilities.
Repeat.

Infinite creature LTB

Infinite creature ETB

Infinite creature sacrifice triggers

Infinite death triggers

Felothar, Dawn of the Abzan

Cryptic Trilobite

Crystalline Crawler

Emiel the Blessed

Basking Broodscale

Activate Emiel the Blessed by paying {3}, blinking Felothar.
When Felothar enters the battlefield, it and Blessed Sanctuary trigger.
Resolve the Blessed Sanctuary trigger, creating a token.
Resolve the Felothar trigger, causing you to sacrifice a nonland permanent and put a +1/+1 counter on each creature you control.
Activate Crystalline Crawler by removing a +1/+1 counter from it, adding {1}.
Activate Cryptic Trilobite by removing a +1/+1 counter from it, adding {C}{C} that can only be spent to activate abilities.
Repeat.

Infinite +1/+1 counters on creatures you control

Blessed Sanctuary

Combos with "Felothar, Dawn of the Abzan"