The Beholder is a tiny observation structure that can be built practically anywhere, even on the side of steep cliffs. It's hidden from radar AND line of sight, making it impossible to detect.
It costs -3 energy even while uncloaked, and an additional -12 to maintain its cloak.
It cannot see cloaked units, but likewise, spy bots/stealth tanks etc. cannot see the camera. If you set a staggered line of them in a gap, any cloaked units moving through it will be revealed when they unwittingly blunder into one.
Set cameras to watch over any contested ground to defeat radar jamming—especially useful vs. Sharpshooters paired with a Smuggler.
Beholders are instantly destroyed by a Juno missile.