Dark Insight

At-will, swift, ranged; you peer into a creature's heart and learn one of its inner resentments, grudges, fears, or weaknesses (Cha negates). Each further use on the same target reveals another.

Knowledge is a weapon. When you or an ally exploits a revealed weakness — speaking the resentment aloud, targeting the weak flank, invoking the feared thing — that check or attack gains advantage. Against groups, voicing the right resentment at the right moment can turn subordinates against their leader (GM's discretion, with advantage on the relevant social checks).