So vicious mockery is, to my understanding, the bard insulting a target, and the target taking psychic damage, and gaining disadvantage.
The flavor, as I understand it, is that they're so insulted it actually hurts.
Which lead me to wonder – could a bard get a vicious mockery off, and the target not know they've been attacked?
Of course, the target knows they've been viciously insulted, and assuming they fail their Wisdom check, are mad at the bard and would probably like to murder said bard. But, if they're all in a bar, and the target wants to attack the bard (attempting to murder him in broad daylight), it seems reasonable that other people would want to stop said murder – after all, it is just a bard insulting someone, and bards do that all the time – it doesn't quite rise to the level of trying to knock his lights out. (Although most of the patrons of said bar are probably fairly understanding of his position…)
To look at a slightly different situation, if a wizard cast fireball on a patron, the entire bar would be up in arms attempting to lynch said wizard. Would there be a similar effect on a bard mocking someone?
So I guess my question boils down to: Do other people recognize vicious mockery as an actual attack, or do they simply think it's a devastating insult?
Best Answer
Debatable: but it's still insulting
The general rules for spellcasting suggest that when a spell has a verbal component, this may be more than any common speech you must make to cast the spell. As an example, Jeremy Crawford indicated that for the spell Suggestion to work:
But Vicious Mockery is an unusual case. Not only are its only components Verbal, its description also states:
The word "subtle" in particular may indicate that you can cast this spell without anyone noticing its magical nature. Such an attempt may require an Arcana check on the part of onlookers/the target, or may succeed or fail automatically at the discretion of the DM. (See Xanathar's Guide to Everything p. 85 for an optional rule that applies).
Them's Fighting Words
Whether or not you are known to be literally using your words to fight an opponent, you could definitely be seen as issuing them a challenge by literally viciously mocking them.
Is your society one where duels are legal? Where besmirching a man's honor is a legal defense for retaliation? If so, your perceived insults may give as much provocation as an actual attack.
And even if insults are not legally considered provocation, beware social norms. If you assume that after you have brutally insulted a person in a bar, everyone in the bar will leap to your defense if the insulted person proceeded to attack you (or that the insulted party will simply sit there and accept your perfectly legal insults), you may be disappointed in your strategy's results.