“The stag had been showing me my strength—not just the price of mercy but the power it bestowed. And mercy was something that the Darkling would never understand.
I had spared the stag’s life. The power of that life belonged to me as surely as it belonged to the man who had taken it.”
This is the moment in Chapter 22 that Alina understands the true nature of the stag’s antlers—and why the stag has been haunting her dreams—and regains control of her powers. In what can only be described as an epiphany, Alina realizes that the mercy she showed the stag by not killing it in the grove gave her power over it just as completely as the Darkling got by slaying it. This quote represents not just the climax of the book, where Alina seizes her powers and wrenches control of her life back from the Darkling, but its moral center. In the face of his cruelty, mercy becomes the force that Alina can use to undermine the Darkling’s control on her. Moreover, the Darkling’s inability to understand the power of mercy itself is what makes it possible for Alina to escape with Mal. Had the Darkling not been blinded by hubris, he may have understood the power that mercy bestowed on Alina and taken measures to stop her.