There's no explanation on how the entity limiter works for nations, which makes creating farm designs at time frustratingly difficult, when some of the mobs suddenly die and the farm becomes much less efficient than anticipated. Nations definitely isn't using Towny's entity limiter (or at least with the same setting), because after testing I could put maximum 20 sheep in an 8x8 area, which shouldn't be possible if the limiter is the same, which was explained that maximum 12 sheep can be next to each other.