Cryptic Trilobite have at least one +1/1 counter on them.
Deadeye Navigator is paired with your commander.
Mana Needed
({1} magic symbol) ({U} magic symbol) available.
Steps
Activate your commander by paying ({1} magic symbol) ({U} magic symbol) , blinking it.
Your commander enters the battlefield, triggering
Deadeye Navigator's soulbond ability and
Norn's Choirmaster.
Resolve the
Deadeye Navigator, repairing it and your commander.
Resolve the
Norn's Choirmaster trigger, 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 ({U} 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.
Repeat.
Results
Infinite +1/+1 counters on
Cryptic Trilobite.
Infinite colorless mana that can only be spent to activate abilities.