Shadow and Bone by Leigh Bardugo (z-lib.org).mobi

most valued Grisha had just punched his second in command.
Pull it back. The command rang through me and I looked at the Darkling in
horror.
“No!” I said. But I couldn’t stop it; the dome of light began to contract. Mal
looked at me as the circle shrank closer to the skiff, and if Ivan hadn’t been
holding me, the look of regret and love in his blue eyes would have sent me to
my knees. I fought with everything I had, every bit of strength, everything
Baghra had taught me, and it was nothing in the face of the Darkling’s power
over me. The light inched closer to the skiff.
I gripped the railing and cried out in rage, in misery, the tears streaming down
my cheeks. Mal was standing at the edge of the gleaming circle now. I could see
the shapes of the volcra in the swirling dark, feel the beat of their wings. He
could have run, could have wept, could have clung to the sides of the skiff until
the darkness took him, but he did none of those things. He stood unflinching
before the gathering dark.
Only I had the power to save him – and I was powerless to save him. In the
next breath, the darkness swallowed him. I heard him scream. The memory of
the stag reared up before me, so vivid that for a moment the snowy glade swam
in my vision, the image of it transposed over the barren landscape of the Fold. I
smelled the pines, felt the chill air on my cheeks. I remembered the stag’s dark,
liquid eyes, the plume of his breath in the cold night, the moment when I knew
that I would not take his life. And finally, I understood why the stag had come to
me every night in my dreams.
I’d thought the stag was haunting me, a reminder of my failure and the price
my weakness would exact. But I was wrong.
The stag had been showing me my strength – not just the price of mercy but
the power it bestowed. And mercy was something 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.
I gasped as understanding flooded through me, and I felt that invisible grip
falter. My power slid back into my hands. Once more, I stood in Baghra’s hut,
calling the light for the first time, feeling it rush towards me, taking possession
of what was rightfully mine. This was what I had been born for. I would never
let anyone separate me from it again.
Light exploded from me, pure and unwavering, flooding over the dark place
where Mal had stood only moments before. The volcra that had hold of him
shrieked and released its grip. Mal fell to his knees, blood streaming from his
wounds as my light enveloped him and drove the volcra back into the darkness.