I can certainly confrim that you will get Speak with Dead even if you pass only one wisdom check ...
I have the feeling that you will get it even if you fail even first wisdom check, but im not exactly sure about that one right now. :-/
Therefore i dare to presume that its only first of possible rewards ... that is not yet implemented.
Either that, or you need to have (again not yet implemented) Necromancer specialization to get its full potential.
Hmm, interesting. If it actually has additional rewards locked behind the second and third checks then I can definitely get behind.
Considering there's a penalty for also failing the same skill checks that gradually increase in difficulty I think it'd definitely add a solid sense of "how far are you willing to go?" It's an evil tome after all.
