They are splash weapons and I am not really trying to throw them at any one in particular I'm literally dropping bombs in a crowd of hundreds. No I cannot hit the one square I want but I can hit a large crowd of hundreds. Second, tell me what they can do then? They have no abilities that can reach me they can run and try to take cover in this totally open grassy meadow they are camped in (which we have accounted for) but considering its perpetually night in the demi-plane they don't even know anything is happening until the first bomb hits. Nor can they see where the rest of the bombs are falling so its not like they know which way to run to avoid them. I guess I should have mentioned I have fast bombs so it takes 8 rounds for me to drop all of them.
As far as me doing it repeatedly, the only thing I can come up with is they can attempt to build some shelter. But that requires wood or stone, meaning they have to clear cut or quarry their demi-plane. Don't be a pretentious ass and say Well, I think the comment "know of something to stop me besides just GM says no" pretty much tells me all I need to know about this" when you don't even have a real way to answer my question. If you need more background on something we are doing you can ask me. It would just take a a long time to type it and it was 3 a.m. when I first posted this.
I quoted the comment because that pretty much tells me that if anything happens to dissuade you from doing it, then you'll simply blame the GM. That's not being pompous, friend, just identify the significance of a statement. You are allowed to take that as you will, however.
So, first off, at 1,000 feet high, the only possible thing you could be aiming for would be the campfires. The demi-plane has the "dim light" trait, meaning that it's perpetual night with only star- and moonlight. You wouldn't be able to see anything on the ground except for the fires with a -100 to your Perception check in addition to the nighttime penalties. Secondly, the very text description records "hundreds of campfires," so the allotment of campfires you're throwing at is quite significant, and you haven't any idea how many spriggans are actually huddled around any given campfire at one time. Thirdly, even the spriggans that camp on the open plain are a few miles away from forest or mountain. After a single night of bombarding, they could move camp, set more decoy fires (it certain they have stored wood on hand, else they couldn't keep the fires going to begin with), or even use the additional wood to do the other thing you mentioned and build shelters. Using the mountains to the north as cover against you would be a viable option after the first night. Spriggans have low-light vision, so unless you've got dark vision, you're not seeing better than they are (and that wouldn't serve you any at all from 1,000 feet anyhow), and they have crossbows if you come down far enough to come close to pinpointing them. They've also got worg riders for speedy communication with other camps (and outriders that are always on patrol, so peppering the large area of a camp wouldn't get to these outriders you wouldn't be able to see). That makes them capable of getting help (and yes, there is help that could be gotten to defend your 1,000-foot theory, but I don't know how much your GM wants you to know about this).
And that's just a few of the options and problems. Naturally, you can simply hand wave all this, say you've bombarded the heck out of the camp, expect that all the spriggans are huddled up in a nice little quivering mass of flesh for you, get your XP, and call it a day. And that's cool! Like I said in my last post, if that's your game, I hope you have a blast with it! In the end, if you're having fun and your GM is having fun, then all this is moot anyhow. Collect your XP and go about your business. It's all good!
I wish you all the best, PM. Just have fun, man. =)