Cryptic Trilobite has at least one +1/+1 counter on it.
({3} magic symbol) available.
Steps
Activate
Emiel the Blessed by paying ({3} magic symbol) , blinking
Agent Frank Horrigan.
When
Agent Frank Horrigan enters the battlefield, it triggers, causing you to put two +1/+1 counters on
Cryptic Trilobite.
Activate Crystalline Crawler's first ability twice by removing two +1/+1 counters from it, adding ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) that can only be spent to activate abilities.
Repeat.
Results
Infinite +1/+1 counters on
Cryptic Trilobite.
Infinite blinking.
Infinite colorless mana that can only be spent to activate abilities.