Dragoon on field effect to destroy opponent monster wont activate

During your Main Phase: You can destroy 1 monster your opponent controls, and if you do, inflict damage to your opponent equal to that monster's original ATK. You can use this effect a number of times per turn **up to the number of Normal Monsters used as Fusion Material for this card.**
How many normal monsters did you use as material between Timaeus the United Dragon and Dark Magician of Destruction?