I did search for a similar topic, i assumed this had been a topic before but the only similar i topic was “some maps are too dark”.
The map being dark is not the problem, the map being dark AND the monsters being dark such that you can’t see them well at all is a problem.
Generally this means most of the maps with void creatures in it.
Not sure what the answer is, after all the idea of the void creatures is that they are “dark” and they are not exactly going to be found hanging around in sun drenched fields at midday.
I find those maps very tedious to run and have started avoiding them, but sometimes I can’t…