Here, an alternative to "50% miss chance" would be to give it an attack with a 1-turn cooldown (killed someone today - rest tomorrow, you're still young). Or 2 turns, depending on how "evil" the city should be.
Added 3 minutes later
Oh, while I was writing, someone else already wrote it... :D
Если где-то чего-то убудет, то в другом месте добавится.
(Закон сохранения).