Blackwind Arena

From the back of the book: Your story begins in one of the triangular arenas of the planet Siri Prime, a backwater world at the very fringe of the galaxy. You have been bought by the owner of the gladiatorial school of the Falcon, to be trained, bleed an die for the entertainment of the decadent elite. However, there is one way out: emerge victorious from five battles, five fights to the death, and you will earn your freedom once more.