the on field effect that says “Special Summon 1 “Artmage” monster or 1 “Medius the Pure” from your Deck, also for the rest of this turn, the activation of your cards and effects that include an effect that Fusion Summons a Fusion Monster cannot be negated, also your opponent cannot activate cards or effects when a monster is Fusion Summoned this way.” doesn’t work because in the same turn after i successfully resolved the card, the effects that fusion summon a fusion monster have been negated not one but two times
Do you have a replay?
The effect can still be negated, the activation cannot be negated. So they can Imperm the Power Patron owl guy, but they cant use Baronne de Fleur to negate the activation.