One of these abilities is "incite unrest". Across several turns, this can enable a war of attrition ( a turn represents a year or a season I cannot remember). Death by 1000 cuts is a way to reduce the morale and economic output of a city in order to eventually conquer it.
Here is an excerpt from a forum dialogue about the game:
"Incite Unreast give "X" public order penality, depending on your agent skills and traits. Army gives "X" public order boost depending on army size and general traits and skills.
So yes.
The best tactic would put as many agents as you can get into far positions, champions can decrease public order as a passive, spy like you already know they pay for it, armies can raid, which decrease their upkeep and steal some of their income for youself."
https://steamcommunity.com/app/214950/discussions/0/61956934...