Bulbrusk the Bulbous in Contested H3 has the buff 'Mushroom Council' that stacks from adds, and decrements if adds are mezzed, stunned, or feared - but strangely charm is omitted, unlike other buffs of that type. One of his types of adds are charmable, but charming them didn't seem to reduce his increments. This is different from most buffs of this type, so wasn't sure if it was intentional or not.