It would be unusual, to me, if there were no spell in the world that could "feedback" (as my DM puts it) on the scryer. We're usually really creative about this sort of thing, but on this we have no ideas.
Otherwise, besides continuing to try to detect the scrying orb and then casting a spell (or throwing a thick blanket over it), or spending all our time in deep caves, there is nothing we can do.
I suppose we might be able to detect person somehow? That, at least, would be something—though we do not know who it is who is scrying. We just know that it's happening regularly ('cause we are such big heroes, and about to try to foil a war, is why).
Details and clarification
- They have a lock of hair from several of our number that were given up many sessions back when they wanted to be seen doing heroic stuff...
- We have a Lantern of Revealing, I think it's called, that reveals all invisible things, and it has several times revealed the orb that is the "camera" for scrying. In our game we have become the leaders of those fighting a distant evil Iron Empire; they are trying to figure out how best to beat us.
- What we are looking for is a way to zap them in the eye, using the energy that is their scrying beam thing, that would be a best solution, but the core problem is that we feel powerless. We'd settle for whatever can counter the scrying on our party.
- We are level 9, and we have two Clerics, a Ranger, a Rogue and a Fighter. I think that's right. Actually, they are so much more than those things... :-) but that's what you really need to know.