Poisoned Tongues

It’s time consuming to slenderize a rival, but sometimes humiliation is preferably to stabbing them. Roll Manipulation + Politics if you want to ruin a reputation in a royal court or formal temple hierarchy. Roll Manipulation + Etiquette if you want to ruin someone’s reputation among commoners in a tavern or marketplace.
Difficulty is based on the reputation of the target. It’s easier to lambast the court bumbler but throwing darts at the hero of the hour is difficult to do without looking petty. One success plants doubt and five successes likely radically turns opinion forever. A botch either has the opposite intended effect or creates a public feud if not both.
Campaigns of whispered insinuations and slander often takes months to reach fruition. Note, it can take dozens of such manipulation to have any impact on a court or large population center as a whole.
If insinuations are not enough, a frame-up can be preferable but that it should probably require a wide variety of rolls and actions to work.