It's the reason why I suggested a city guardian. And they have one now within the statue! Sadly, I've never seen it in operation yet...so I can't comment as to it's balance.
It is very very poor. I would not for a second hesitate or change the way I made my sov/army composistion knowing it was there. They should atleast lose the first level statue and make them all guardian idols. Atlest the AI could cast spells each battle.
While I don't want cities to be an easy pushover, you have to be careful about making them too autonomous. The last time we had this discussion, my stance was that there is already too little impetus to build your own troops in this game, and cities with strong self-defense will only further deflate the need to build troops. I haven't seen anything to massively change that paradigm in the last few betas and I stand by it. Sure, I think a city shouldn't be able to be knocked over by a lone sov on turn 15, but they shouldn't be self defending against troll armies on turn 120 either.
I see what you are saying but I must disagree. The reason why there is few troops is that Hero are so much better at every occasion. You cant solve that problem by making cities weak, in fact I argue you exacerbate it. Want better defence for
A. I hate monsters killing my cities early to mid game. It feels weak that a few spiders/wolves/bears can kill my city. It frustrates me and even if I try and put a troop or two in a city it usually dies anyway, no real difference, but a big cost.
Current Answer: Rely on heros to clear area. Too bad so sad if you say, made them govenor or otherwise tried to mix up your playstyle.
B. I hate wondering super monsters - Dragons, Hoarderspiders, etc Taking out my city at any time. Troops will not stop these without huge investment if at all. This I think is a monster rules/AI issue, not a city defence issue
Current Answer: Do your best with your heros to stop them. Or better yet, get attacking the much easier to kill AI and make sure you have plenty of cities to spare!!!!
C. Steamrolling AI. AI for whatever reason often has little city defence/junk. I go from city to city (often within a turn or two) with my heros taking out his cities.
Current ANswer: None, use willpower to not crunch AI
In all three cases the answer is never build more troops dont use heros. Its get your heros going as early as possible.
Giving cities a massive boost that the AI cant take away or mismange and doesnt require huge changes to the game is the goal. If done right it would make it necessary to perhaps atleast REST between city assaults, ideally, even having to gett some troops to help out my heros.
So I dont see extra city defence in any way encourages heros.