Board Thread:Bug Reports/@comment-27516710-20160901195709/@comment-27516710-20160915025521

What tends to happen in the Misties or Gray Mountains for example is they spawn along the side of the slopes (sometimes in the air) so they fall down and collect below. If it's based per chunk then you end up with the spawning chunk being empty while the ones that make up the lower elevations pile up more mobs than they should. So those chunks don't spawn more but you end up with an endless cascade of mobs falling down the mountains. Where the river cuts through between Isengard and Rohan makes the issue even worse since you then end up with piles of mobs in the water trying to get somewhere. Bannering those trouble spots can help but it's just not possible to do this everywhere where there's significant slopes. Decreasing the spawn rates in biomes with large variations in elevation would help reduce this problem.