Powerful Plum Hexmallow

Marshmallow Magic This marshmallow has a rich, plum flavor with a robust undertone of blackcurrant. It buzzes softly like a bee when you touch it.
  You can use a bonus action to eat this marshmallow, when you do, your abilities, attacks and spells ignore any resistance to Force damage a target may have until you finish a long rest. However, for the duration you also are vulnerable to Force damage. If you are resistant, you lose the resistance. If you are immune, you become resistant. For the duration, you cannot gain the benefits of any other hexmallow.