I have fusion summoned Secreterion in my field, my opponent has an exciton knight on their field. He activates the effect on Genia of the Ring, targeting his own Exciton Knight, to special summon itself and change the targeted monster into a Spellcaster.
Can he activate the effect of exciton knight on resolution, or is it prevented by the effect of Secreterion that states that "While you control this Fusion Summoned card, your opponent cannot activate the effects of Special Summoned Dragon or Spellcaster monsters they control.", since exciton knight is now a spellcaster?
