Duelingbook Forum

So, this came up in one of my duels...

I summoned Magician of Dark Chaos MAX with Secrets of Dark Magic during my opponent's first SP.
At this point, I controlled Apprentice Illusion Magician (a dark monster) and Magician of Dark Chaos Max (also dark, obviously).
On summon, I tried activating my ritual monster's effect, with the cost of tributing Apprentice.
My opponent told me to wait and activated Super Polymerization on my ritual monster's summon, and said that he has priority as the turn player so he can activate it before I can activate my own effect and that I can't use my ritual monster's on summon effect because of super polymerization's effect that says that cards or effects can't be activated in response to it.
I wasn't sure about what happens in this case, so I didn't say anything and let him go with it.

Now my question is, what is supposed to actually happen, in that exact situation? Was he correct, or did he misjudge the rulings?
Note that if my effect was to activate first, by tributing Apprentice with MAX's cost, I would make it impossible for him to chain Polymerization afterward, because there wouldn't be enough monsters on the field to use for a fusion summon.

And generally, how does Super Polymerization work against on-summon effects, in similar cases?

It's true that turn player has priority, however your ritual has a trigger effect on summon. Trigger effects always activate before quick ones (like super polymerization). If it was possible to activate super poly before your ritual's effect, then he would be correct and you wouldn't be able to chain to it.