The battle at the end of the book that the Doctor and The Master had. Due to The Master making it out alive with only a missing ear, he is the physical winner of the battle, as the Doctor regenerated into his next incarnation due to his injuries. The mental winner of this battle was the Doctor, as he did not lose his sanity from trauma after the battle. The Master grew to believe that everyone but him must be killed, and he inspired Tigerstar to become evil for him, not Thistleclaw.
So it is unclear who exactly won the battle at the end of The Final Game.