Just have your mates focus adds first and keep an eye on Valus. They systematically spawn in two separate groups based on time in the arena and his health. Manage them and you can control the fight with incredible ease with the slight exception of a Psion getting sneaky (Just use the Motion Tracker, especially Hunters, have Knucklehead.) Word of Crota helps a ton on the Psions. Solo? Ehm, probably not.