The Necromancy book can be found on the 2nd floor of the Legerdemain Lounge. It spawns on the empty bookcase in the northwest bedroom.
Ledgemain lounge downstairs.
Im sorry theres only 8 books in total here is map!
Ideal Route!
1. Starting at the teleportation room (1), check the floor for the book, and then exit the building to the east.
2. Mount up, head southwest, and enter the Violet Hold (6). Run halfway to Archmage Timear and check for the book on the box.
3. Turn around, exit the hold, and cross the street to the Dalaran Visitor Center (2). Check the floor for a book, and then exit the building the same way you entered.
4. Mount up and resume running southwest. Bear right at the southern tip of the central square and continue northwest to the Violet Citadel (3). Upon entering the building, check the left bookcase for a book.
5. Continue up the stairs and bear left at the top. Check the floor between the bookcases (4). Then jump off the balcony onto the lower level of the citadel. Exit the building and immediately mount up.
6. Cross the street, head up the stairs and bear left until you are under the sign for The Wonderworks. Zoom out and adjust your view to check the small box on the upper balcony of The Threads of Fate (5). If the book is available, proceed to its location. Otherwise, continue up the street, heading northeast.
7. Continue heading northeast until you reach the northern tip of the central square. Bear right and enter the Legerdemain Lounge. Check the empty bookcase next to the stove (8), then head up the stairs on the left.
8. From the top of the stairs, run to the center of the green rug in the hallway. Check the empty bookcase in the bedroom directly across from you (7), then head out onto the balcony to your right. Jump down, mount up, and then bear right. Continue southeast to the teleportation room (1).