Matras has asked you to bring him the blueprints of the Tower to fulfill his curiosity. It is reported that Ranku and the Demon Prince have the blueprints.
1. This quest starts on Hell Bound, where I cannot say since I don't yet have a working map. The area Matras is in open up at stage 9 on Hell Bound, according to NCSoft. He asks you to retrieve blueprints from the tower, from the Demon Prince and Ranku. He gives you some items that are supposed to help you with this task. They appear to work exactly like regular Fire/Water/Earth/Wind/etc stones and can be applied to your weapon.
Needless to say, this quest is incomplete, more will be added when more areas of Hell Bound are opened up.