Post: #3

I once saw an "invisible" npc on a long gone server. They patched a very small animation (in this case it was a dagger) as if it was a character.

The NPC attacked you, but the only thing you could see was the moving dagger.

Perhaps something like this could be a possible solution?
Every time you cast spirit speak, a function changes the body of the npc to a real ghost, insted of the (in my example) moving dagger.

I know that this is not a very good solution, but at least it should work.