There is a really good series of walkthroughs on the Arena and all its fighters starting here:
Part 1: http://www.rarityguide.com/articles/articles/2515/1/Game-of-Thrones-Walkthrough-Part-54--Alester--Blood-On-The-Sand-Part-1/Page1.html
Part 2: http://www.rarityguide.com/articles/articles/2516/1/Game-of-Thrones-Walkthrough-Part-55--Alester--Blood-On-The-Sand-Part-2/Page1.html
Part 3: http://www.rarityguide.com/articles/articles/2522/1/Game-of-Thrones-Walkthrough-Part-56--Alester--Blood-On-The-Sand-Part-3/Page1.html
Good luck, and try not to die. :)