My opponent controlled "Endymion, the Mighty Master of Magic" on their Pendulum zone and has 6 Spell counters scattered on his part of the field. I controlled 2 face-down cards on my S/T zone, one of which is "Starlight Road". My opponent activates the effect of "Endymion, the Mighty Master of Magic" and removed 6 Spell counters as cost.
Can I activate "Starlight Road" in response to "Endymion, the Mighty Master of Magic" Pendulum effect?
Pendulum Effect:
You can remove 6 Spell Counters from your field; Special Summon this card from the Pendulum Zone, then count the number of cards you control that can have a Spell Counter, destroy up to that many cards on the field, and if you do, place Spell Counters on this card equal to the number of cards destroyed. You can only use this effect of "Endymion, the Mighty Master of Magic" once per turn.