Crumbling stone barn in Serdica

[Superba]

With the "showmeall" option I can see lots of red points downstairs after killing the rats. No enemies on ground level outside in the fields.

I state I already finished the game twice, I believe I know there's no quest in this part of Serdica neither now nor after.

So, do I miss a switch somewhere underground in the barn?

[Randomizer]

Were the red dots in the two rooms that open when you reach the north end of the lower level? They may be the spawn points and just stay after killing them.

[Superba]

No they were ouside the walls, north and east. I went back here and they were disappeared. Maybe the rats were hallucinogen, however you state there's no secret chambers there and that is conclusive.

[Jerakeen]

If they're outside the walls then you're probably seeing something that's in another building. All secondary (ie indoor or underground) areas of a zone are in the same "layer"; even though you can only see the map of the building you're in, showmall will display creatures in the whole layer.

 

Or as Randomizer says, they could be spawns.

[Earth]

there are ~10 red dots (and 1 big green (I think) in corruption underground area (west from Monitor C) and 1 right behind that forest somewhat nw from Mon C and plenty of green dots north of Troezen trove (underground) and some green dots everywhere in unaccessible places.