The Spellbreaker

Walkthrough
This quest starts after you have brought Philippa to her quarters after you decided to rescue her instead of Triss if you took Iorveth's path in Chapter 2.

in the room next to the living room, the table will have notes with picture, you will need that to unlock the chest when you go up stairs.

You can copy down the 3 diagrams in the picture. Use the left most one.