The Way of Shadow says that creatures (or perhaps “extensions” might be a more fitting term) of the Lying Darkness can be harmed by weapons of crystal.
What about beings of Jigoku or the Shadowlands or practitioners of blood magic — could their maho (offensive magic) or Oni powers (either physical or supernatural) harm such beings as well?
I'm working from the first edition of L5R, but lore from later editions will do.
While there isn't any actual rule for that particular situation (that I know of), it has been said that prior to Fu Leng's resurrection, the Lying Darkness was too afraid of the Shadowlands to make a move. I've always ruled that if there is a price to be paid (such as the Taint), the offense would be more effective.
Otherwise, you may compare Void versus Taint, named Oni versus spawns or Taint Rank versus Shadow Points.
These are two different realms. Two different dimension of living matters. Like two different planet. One from the Nothing and the other from Jigoku. There is no rule about if they cannot effect on each others. If there isn't a strict rule in similar cases, I prefer to handle the situation like they can effect each other. What is very important, while Fu Leng and Shadowland creatures are evil, the Nothing is not evil. Fu Leng has a history how he became evil and opened a gate to Jigoku to the realm of the evil. The Nothing is just working on to be again nothing else but Nothing. Nothing cannot have feelings, because it is something.
