Girl Genius XIII: "Gott's Leedle Feesh in Trousers!"

[Imgran]

They can also be unstoppable, but come with a cost. Perhaps there is a very large chance they will do more than requested to do, in ways you do not want them to.

Or perhaps they're like the Uligb in Buck Godot -- more than powerful enough to be going on with against most threats, but they have their own priorities and ways at looking at the world that makes them not useful in all situations. Or some other kind of flaw that can be exploited by someone expecting to encounter a Dreen.

As for what that flaw is -- could literally be anything. It could be that they're omnicidal maniacs, and thus very unpopular to unleash in an empire where the Baron, powerful as he is, still counts on at least some nominal support to keep everything from falling apart all at the same time, or it could be as simple as having a hole in their perception of color such that you can hide from them with perfect ease while being covered head to toe in any shade of the color purple. Or really anything else that you could imagine. That's the joy of a new, still not very well exposited, threat.