"You have to click and watch the video to see what song it is...."
I watched; it's "Quake II - Descent into Cerberon" - Quake II soundtrack Music by Sonic Mayhem
A Gladiator Dies Only Once by Steven Saylor. Great series. Great character. Set in authentic, meticulously researched ancient Rome, reminds me the real thing is way more gritty than fictional settings, whether Thieves World or Game of Thrones.