Cryptic Trilobite has at least two +1/+1 counters on it.
Steps
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.
Activate Sliver Queen by paying ({2} magic symbol) , creating a 1/1 Sliver creature token.
The Sliver enters the battlefield, triggering Cathars' Crusade, putting a +1/+1 counter on each creature you control.