Just wondering can you chain Starlight Road to this card?

My thinking is at first you don't know how many face-up monsters will get destroyed until the card resolves, but I could be wrong.

Could be used as a nice addition to dark hole.

Removing all Magic Cards in your Graveyard is the cost to activate and the destruction takes place when it resolves.

As long as that player would have 2 or more of their cards (just monsters in this case) destroyed by Rampaging Magic Power/That Wacky Magic (lol), then they can chain Starlight Road to its activation since it is "guaranteed" that the opponent would have 2+ of their monsters destroyed (as in there's no coin toss, option to not destroy, dice roll, or missing the timing of activation).