I've known about this secret area that has 75 vials and 150 spirit points but never how to access it.

I've looked at old walkthoughs and such that say it opens after defeating the first 5 bosses or just once you have the Sword. Neither of those turn out to be the case. Simply having the Torch turned on in your inventory and going down there reveals the secret.

Not sure if anyone else had figured this out yet so I thought I'd make a post.