Spirit of the Night, and Mirrored World?

[Bluflare1]

So basically the lost can go in the mirrored world, and you can go in when you hit the white fire which turns you into the lost which is a ghost.

But why not Spirit of the Night aren't you literally a ghost using that power up?

I mean like would giving you a holy mantle when you enter it with spirit of the night make it worth it?

Honestly I feel like if you have spirit of the night as a non lost character since you are pretty much a ghost going in there without a holy mantle would not be so bad, but maybe to balance it maybe taking 2 hearts of damage would be a good idea?