Night of the Berserkers by Lee Savino

I have one night to meet the mage…
One night to destroy him…
One night to break the Berserker’s curse…
One night to save them…
I woke in a field, surrounded by warriors. The spell had brought me to the threshold of the Corpse King’s fortress. When the men seized me, I reached for my power, but none came to my aid.
I was a thousand years from home, a captive of the Corpse King’s guard, and I had no magic.