Phoebe
Phoebe is a wilderness planet populated by fierce tribes of aboriginal natives. Very few expeditions to Phoebe have made it back to civilization without significant loss of personnel and equipment. The tribes are singular in being able to thwart any technologically superior Defense with their selfless unity and stone age tools. It has never been determined that there exists anything of value on Phoebe due to the lack of survey information. Orbiting Phoebe are warning buoys warning potential visitors of the danger.