Yea gold really is of no use in this game as you can get all the weapons, armor and potions you need by looting or using people in your battle tower. I did not use gold once in this game, never even used my runners as you can hold 50 gems/ingredients or a type in your inventory in one slot before it starts another slot.
I had at least 50 of everything besides Malachite gems, had 13 of those in inventory when I finished the game.
Oh and Black Rose, that was another thing that was hard for me to find but I never used them anyways as I never made potions just used the ones I found/looted.
