Just tested it. Had a city with a garrison monsters still attacked it. Unless this works differently for the AI, having units stationed in the city does nothing to deter monster attacks on cities of Civs with Stealth.

I think the mechanic in general is wonky right now. Besides my prior examples, was playing a Civ with Stealth, monsters attacked my army anyway.

Not sure that city unit strength is factoring in all the time either. A lone Butcherman attacked my capital, Fortress with upgrade, Adventure's Hall, and 3 heroes sitting in it. Auto resolved sense it was Weak (Butcherman) v Strong (City Forces).

I've been getting a feel for the game playing on the normal difficulty level. Two full games and I have seen the AI both attack and be attacked by monsters as well as complete certain quests/events on the map. Relias (The red guy, I think that's his name.) even wiped out one of the large elemental lords and settled in the area it had been wandering.

It's either the A.I. are attacking and killing each other, or the mobs/units are randomly disappearing for some odd reason. I forgot to check his cities after I took him over to see if I could find the trophy. Anyone know where that would be located in the city menu?

One thing I have never seen, however, is AI beast/ruffians/monsters attacking and sacking cities. Maybe that occurs on higher difficulties only?

Either way. From the sounds of it, it could use some tweaking.