Best in the Elf-ing World — Billy Wong

THIS SERIES IS MEANT TO BE UNREALISTIC FUN. If complete believability is a must, it might not be for you... but if you like the sound of an awesome female brawler standing toe to toe with huge men and monsters in brutal fistfights on sheer toughness and badassery, maybe it is.

When the world's greatest mixed martial arts fighter challenges goth singer and ultimate brawler Freya to a match, she eagerly accepts the chance to battle a legend. To her surprise, she soon receives an offer of training from an otherworldly visitor. What she doesn't know is that her elvish benefactor has plans for her beyond just a celebrity cage fight.

A short story. Fourth chronologically in the Gothic Warrior series, but the stories do not have to be read in order.