A Destiny Knot is a held item. If the holder of the Destiny Knot is afflicted with the infatuated status by an opponent, the opponent will also become infatuated. If a Pokémon holds a Destiny Knot while breeding, five of the parents' IVs will be passed to their offspring instead of three. It can be obtained as a tier 3 special drop. It is a possible drop from uncommon and rare boss Pokémon.
Trivia
Before Reforged, this item had the following recipe. It was removed due to many held items being far too easy to make.