Lorelei Bell 
Crescendo [EPUB ebook] 

A profound change has left Sabrina powerless at a time she needs her abilities the most.
Determined to save Tremayne, she gives him a life-changing gift. Weakened from the attack, Sabrina is abducted by a group of powerful witches, who are planning to drain her powers for their own benefit.
In the middle of a power-hungry vampire conflict, can Sabrina take the next step towards her future, or will her absent powers and strained relationships be the end of it all?