Cryptic Trilobite has at least four +1/+1 counters.
Steps
Activate Cryptic Trilobite's first ability by removing two +1/+1 counters from it, adding ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) .
Activate Ghave's first ability by paying ({1} magic symbol) and removing a +1/+1 counter from Cryptic Trilobite, creating a 1/1 Saproling creature token.
The Saproling enters the battlefield, triggering Sigil, putting two +1/+1 counters on the Saproling.
Activate Ghave's first ability by paying ({1} magic symbol) and removing a +1/+1 counter from a Saproling, creating a 1/1 Saproling creature token.
The Saproling enters the battlefield, triggering Sigil Captain, putting two +1/+1 counters on the Saproling.
Activate Ghave's second ability by paying ({1} magic symbol) and sacrificing a Saproling token, putting a +1/+1 counter on Cryptic Trilobite.
Activate Cryptic Trilobite's first ability by removing a +1/+1 counter from it, adding ({C} magic symbol) ({C} magic symbol) .