Vous avez cherché: an excellent day (Anglais - Latin)

he that hath knowledge spareth his words: and a man of understanding is of an excellent spirit.
qui moderatur sermones suos doctus et prudens est et pretiosi spiritus vir eruditu

then this daniel was preferred above the presidents and princes, because an excellent spirit was in him; and the king thought to set him over the whole realm.
igitur danihel superabat omnes principes et satrapas quia spiritus dei amplior erat in e

let the righteous smite me; it shall be a kindness: and let him reprove me; it shall be an excellent oil, which shall not break my head: for yet my prayer also shall be in their calamities.
considerabam ad dexteram et videbam et non erat qui cognosceret me periit fuga a me et non est qui requirit animam mea

there isn't one way to do so, and there's no special language that can be applied to every curse, though certain themes and vocabulary are frequent and sometimes "magical" gibberish is used in incantations. lead tablets are frequently preferred for their longevity. one standard work that includes far more than latin texts is gager's curse tablets and binding spells from the ancient world], though i highly recommend everyone check out daniel ogden's magic, witchcraft, and ghosts in the greek and roman worlds, an excellent sourcebook with tons of curse examples.
cum execratione maledicta congessit