The Scroll is made of the thinnest paper, but it refuses to tear in your attempt to open the seal. The words of the scroll refuse to be known, but you can feel the babble of its unnatural contents begin to flow through your mind, obscuring your thoughts. His word is not known to you, but His will is. You must wander, and you must bear the world.
Tome Unlock : After defeating the summoned creatures, The Herald won't be summoning any more of his creatures. Defeat him and he may have a grey item called "Profane Writ" on him. That will go into your regular inventory and not the quest inventory. Right click on it to unlock this tome.
If you take long enough killing him he will respawn his Minion of Flame, the cooldown is about 3-4 minutes.
This tome unlock contributes to the The Herald pursuit achievement.