Mobs from this mod can spawn in special biomes like the ones listed above. The gimmick of Mushroom Fields is that there are no hostile mobs at night except for Phantoms and the gimmick of Deep Dark is that there are no mobs except for the Warden. This is very annoying, as missed AOE attacks from these mobs kill off the limited Mooshroom population of mushroom biomes and them fighting each other or the player easily alerts the Warden.