How to prep for NGB on very hard and master ninja?

I've beaten basically every version of every game on the hardest difficulty (sigma 1, 2black and 2og, 3re and 4) except for black. I'm on hard difficulty and what I've been doing is using 5 elixirs and 2-3 great elixirs to prep myself , but after getting through chapters 6-7 , that whole catacomb area with like no shops at all, especially right before Alma, I'm genuinely curious as to what I'm gonna do. Not that Alma is particularly difficult for me , but it just seems like that whole underground part is gonna be a slog to get through so I'm curious as to how anyone who has beaten black on its hardest got through it