On the forum i found that :
"After the sewers when youre currently at the library catacombs and youre almost near the FINAL EYE...
You may cast Barretta's perception and a Wraith will appear... He is UWE BECKER and if you manage to beat him... he will drop a NINJA MADU which enable you to HITx3 Randomly...
Where exactly is the ghost? I casted "Perception" a few times and walked the whole room near the final eye but he didnt even shown....am i in a wrong place?