The Souls of Westmarch

The Souls of Westmarch is a tome found in Act V of Diablo III. Written by Urzael, it is dropped in the Zakarum Cathedral by Kasadya after she is defeated.

It reads as follows:

''We must do everything in our power to slow the nephalem down so that the collection of souls is not interrupted. It is the key to Malthael's victory.''