Crystalline Crawler and Cryptic Trilobite have at least one +1/1 counter on them.
({2} magic symbol) ({C} magic symbol) available.
Steps
Activate Eldrazi Displacer by paying ({2} magic symbol) ({C} magic symbol) , blinking your commander.
Your commander enters the battlefield, triggering Norn's Choirmaster, putting a +1/+1 counter on Cryptic Trilobite and Crystalline Crawler.
Activate Crystalline Crawler's first ability by removing a +1/+1 counter from it, adding ({1} magic symbol) .
Activate Cryptic Trilobite's first ability by removing a +1/+1 counter from it, adding ({C} magic symbol) ({C} magic symbol) that can only be spent to activate abilities.