This thing, not very subtle, is a Lurking Eye. You would think a spy is supposed to be hidden, to disappear in the landscape. The Demon Clan doesn't feels the necessity to hide it's spies, since they're strong enough to pulverize those who try to put them out of action. The Lurking eye, conjured by a Black Demon, has some powers related to black demons. They possess the ability to put their victim into a non-gravity zone that lasts just enough to get them high into the air, and then they crash to their death on the ground. If you see these things, never, ever let them attack first. Anyway, if you spot one, be sure the Demon Clan saw you...