Divine message board:
A - Oh no, I took a nap, and now there's a demon infestation!
B - Those things are such a pain, it's nearly impossible to get rid of them once they get a few dungeon cores installed.
C - Hahaha! Suckers!
D - Ugh, can't believe you haven't gotten banned from this forum yet.
A - It's a lot more than a few cores. There's already been an ongoing war between the people I made, and the invaders now. Cores are scattered all over. Help!
C - [message deleted by mods]
B - What kind of help are you looking for?
A - I want to end this war. I was trying to create a world of peace and harmony. This conflict is wrecking it all.
E - Here, take this: [attachment]
A - Uh, thanks? What am I supposed to do with it?
E - Stick it in one of those empty cores between the two sides.
A - Where though? Here's a map [attachment]
E - Core c3. That mountain range should be perfect.

*** Author Note ***

I'd originally intended to use this as the prologue for a reincarnated as a dungeon core type story. Except every time I've tried to write a dungeon core story, I've failed. Doing it right is too much work, and doing it badly is not fun. For any authors out there: Feel free to steal this prologue! I'd be flattered ;)

The original idea was that the demons installed dungeon cores because the cores generated mana, which would make the area more habitable for demons (thought it also caused monsters to spawn). The world they are/were invading didn't naturally have mana or monsters, and was wholly unprepared for an invasion. The god governing the area did create heroes to fight back, and pushed the demons back a long ways, but the monsters and mana interfere with efforts to reclaim the land.

The main character for this story was planned to be a pacifist placed in an ideal defensive position that would prevent armies from either side passing through, forcing peace on both sides.