I’d pick one or two obviously bad guys, the rumoured / infamous necromancer said to live somewhere in the borderlands in a swampy place. Potentially a former battle field where there was some calamity wiping out both armies. The calamity was brought by the city in question. He survived the onslaught and swore revenge.
Maybe a misguided(?) protector of the forest, the town gets rich by exploiting the nearby hills and mountains for their natural resources and they back and slash away at the ancient forest to fuel the mines.
A local noble, was ousted from the city council, had titles revoked and is forced to live in exile. Maybe the noble deserved it maybe not, maybe the Nobel was framed for committing treason, since everyone thinks they are a traitor they might as well show the city what they could really do.
I would not make them all obviously bad guys that gives it more mystery.
Yeah not obvious to me at all. I came to the comments to get enlightened because I did not get the joke.