I feel like a number of things in the quote by Quertus, and suggested by you, can be achieved with Bestow Curse in 5e. Assuming the creature has no more Legendary Saves (which I think are just Portent Dice with DM fiat on the number rolled).
Bestow Curse is a much lower spell than ones that might be able to “instantly kill”. Maybe uses of Hex, or Wish, or other spells, can also be used to debuff a Dragon until a whiny-Player is happy with how awkward the Dragon is acting.