The Book of the Underworld is a powerful ability codex dropped by The Dark Lord, and provides one of the most powerful abilities in the entire game. As this book is an item rather than an ability, it may be cast at any time, not just when the player has no GCD.
Adrenaline requirement: 0%
Cool-down: 60 seconds
Duration: 6 seconds
Whilst under the effects of the Book of the Underworld, players will no longer experience a 3 tick GCD (global cool-down) on their abilities, instead this is adjusted to 1 tick. In real time this is a difference of 1.8 seconds down to 0.6 seconds. Players will also have their basic auto attacks performed 2 ticks (1.2 seconds) faster than usual, this DOES affect legacy mode. Players cannot benefit from ANY healing effects while under the effects of the Book of the Underworld.
As the book makes it possible to attack incredibly fast, players quickly realize that they can unload ridiculous amounts of damage at a high rate, however they must do so at the right moments, or risk death due to being unable to heal. This ability has the most use in situations where you do not need to worry about taking a predictable large hit, or when another player is tanking for you.
It should be mentioned that due to you being unable to heal whilst under the effects of the book, if you were to die with a sign of life (or other) active, you will set to only 1 lifepoint.