To be fair, the spell casters should try their best to bring the dragon to the ground. Otherwise, you are stacking the deck ahead of time and the exercise will illustrate nothing.
Yeah of course, the whole idea will be to bring the Dragon down using Bigby's/Telekinesis or whatever so Henry Handaxe can get in there.
However, I do note, that some posters claim Henry Handaxe simply doesn't need any help because hand axe's are fine.
We'll see how they go.