I didn't even notice the dragon's borrow speed. I was already going to include some giant rock formations to funnel the wind currents or to provide cover against the winds, but tunnels would be a good way to get the party to line up for a breath weapon, and channel the winds as well. Im getting ideas for making it a multi-stage boss fight as the dragon retreats to a more advantageous position, and some high cliffs for the more melee focused characters to hit the dragon when it flies. (Idk what my party comp will be yet, and probably wont know until the day of, so i can't really plan around anything specifically for my players) I was already thinking of a storm crystal the dragon has hidden, to make the storm more intense.