Bonereaper's Hook Notification will notify you when you have completed the requirements to have Professor Putricide's Journal drop. A Raid warning and Notification sound will alert you on screen when this happens. This addon is mainly for those that are not trying to grind out the requirements as fast as possible but for those who wish to just play the game and get a notification when it happens.
Each time you use Apocalypse or cast Army of the Dead it will check both the quest flag and the chat messages from mobs to see if it has completed. If it is complete you will then be notified.
From there you can head to Icecrown Citadel and enter Professor Putricide's Secret lair and kill Stitchwork and receive the hidden Artifact Appearance for Apocalypse.