Originally Posted by
MaxWilson
I have never seen a bard do this and it's hard to imagine that one ever could. Vicious Mockery has pathetic damage and targets a strong save. Even ignoring legendary resistance, a 20th level bard with Cha 20 would have to cast Vicious Mockery 25 times in a row to deal the 178 HP of damage needed to kill even a Young Red Dragon, and it would take 48 castings to kill an Adult Red Dragon. Long before that happens, the dragon will have killed and eaten the bard.
You could kill an orc by insulting it though. :-P
P.S. The disadvantage from Vicious Mockery is decent at low levels and nigh-irrelevant at higher levels, because it only works on one attack. If you Vicious Mockery a CR 5 troll at 5th level, even if he fails the save you're only imposing disadvantage on the d6+4 (7) bite attack, but the 2d6+8 (15) of claw attacks are unhindered.