The Tracer is a mobility restrictor enemy unit. It uses blue laser to trace 3 trajectories around you from its wings and a few seconds later perform high speed shots following them.

Tips
-The Tracer can't harm you, so you can move around freely until the instant the shots are performed.
-Shoot its wings down to disarm the tracer and it will not be able to attack you.
-Shoot to the body inner core center to get a coreshot bonus.