Trilobite Swarm

During your upkeep, put a Spawn counter on Trilobite Swarm
Remove 2 Spawn counters from Trilobite Swarm: Create a blue 1/1 Trilobite creature token.
{1}{u}: Trilobite Swarm gets +1/+1 until end the end of end for each Spawn counter on it. This ability can only be activated once per turn.