@Broly443 idk if this will help but ill share what I did be4 coming across this area. Kill all the carts (3 or 4 total iirc) from Ashen Pass1 all the way towards The Emerald Hall. Then talk to the Ox in The Emerald Hall & he will tell you that he is looking for the kings Mount. & I believe the Mount is disabled in the lava to the right at "Furnace Valley: Valley Entrance" & the Disable Mount will give you a transformation call "Dark Thunder". I also finished Chapter 5 before finding this area
