Nation Effects

[Foodstamp]

I created a nation similar to what you are wanting. I made all the nation units summonable, no recruitables. Then I gave each nation unit multiple domsummons. They spawn anything from nymphs, to vinemen, to fairies to "Forest Zealots".

The Forest Zealots require upkeep, so that takes care of the nation using the freespawns with massive independent armies.

My commanders are all bound to the province they are born in except the Nymph and Dryad commanders. The nymphs have to go seduce enemy commanders to lead the normal units and must use summons such as the Firbolg to lead magical units out of their home territory.

The nation plays really well and is a lot of fun. The AI does not adhere to map movement 0, so it actually plays the mod pretty good as well.

Your idea is slightly different, in that you want your population to die as well. In order to do that, I would use the same method I did, but copy stats from one of the many monsters that kill population, such as the Harvester of Sorrows etc. (Give your units #heal to counter the diseases)