My personal philosophy on Cursing (as in Hexes)*
Disclaimer: When I was younger -- long enough ago that I’ve lived a legal adult’s lifetime in the meantime -- I believed in the literal reality of magic and its power to effect measurable changes in the physical world: blessings, and curses, and divination, and the lot. I no longer do. But my general philosophy on magic (or any other manifestation of personal power, even that expressed by mundane means) remains the same.
Or, you know, just consider this a bit of inspiration for fictional magic.
First off -- Generally speaking, I find it’s more effective to put your energy toward Shielding yourself from harm that hateful people try to inflict on you than it is to try and retaliate (or, in terms of online spaces: it’s better to block than bully).
But, if you’re already in the third chapter of your Villain Origin Story, and there’s no turning back now, and you absolutely must wreak revenge, don’t get swept up in the heat of your rage and go too big. Dead people don’t feel regret, and they don’t spend a lifetime questioning their past choices (and you may have to deal with a vengeful ghost).
Consider the satisfaction in being petty.
May every sweet thing turn to ashes and hair in your mouth.
May a Lego™ materialize on the floor beside your bed on [random prime number-th] mornings
May your butt itch whenever you sit down.
Also, consider making your curses personal. For example: It would be legally just (or at least the most just and plausible) for Donald J. Trump to spend the rest of his life under house arrest.
But that wouldn’t make him suffer as much as having to live out the rest of his days in the anonymity of mediocrity -- to have his fame and celebrity disappear from people’s memories, and have everyone who hears him or sees him recognize his small mindedness, and cease to be impressed by him. To have him enter a room and absolutely no one even notice (not even the cat).
*In terms of language, go for it. Swear like a sailor. Turn the air blue.