Best way to scale a hill?

[Parallel Pain]

if that is the case, get 1 -3 highest armor infantry or heavy cavalry units you have, put them in loose formation and march them up slowly to absorbed all of the missile fire. fast forward, then just go do your thing. just make sure you troops are not tire when you engage them, rest as necessary.

Oh believe me in VH battle with terrain help, there is not one single unit in the game with high enough shield/armor value to stand up to that kind of fire loose formation or not.