Vicious Mockery
"You unleash a string of insults laced with subtle enchantments at a creature you can see within range. If the target can hear you (though it need not understand you), it must succeed on a Wisdom saving throw or take 1d4 psychic damage and have disadvantage on the next Attack roll it makes before the end of its next turn."
- – The spell's description in the PHB
Vicious Mockery is a Bard Cantrip from D&D 5e widely loved for it's incredibly memeable fluff, so much so that nobody seems to realize that the crunch sucks ass.
Why this Spell is Awesome
It gives you an excuse to make a character who's just a nonstop fountain of schlocky one-liners, and the ability to kill the BBEG by insulting their mother. Even better, the clause about the target not needing to understand your language means that, if a bard is nearby, people in this world can suddenly have an emotion breakdown without even understanding why.
You could also slightly reflavor it into your character telling a joke that's so bad that it literally causes some of the victim's brain cells to Ragequit.
Why this Spell is Fail
It's only 1d4 of damage, the lowwest die of damage you can use in 5e. For comparison, Toll the Dead from Xanithar's uses a d8, but upgrades to a freaking d12 if the target is missing even a single hit point. And to add insult to injury, the Frostbite Cantrip, also from Xanithar's, functions nearly identically to Vicious Mockery, save that it uses a d6 instead of a d4. The advantages Vicious Mockery has over Frostbite is that the former doesn't have a somatic component and uses a more rarely resisted damage type, but such things are rarely a consideration in normal gameplay anyway.