You want roshi to survive early stages of the duel in order to allow him to scale. His damage is already okay and the longer the duel goes, the stronger and tankier he becomes (works the same as earth main's passive). Since he is often frontline, ife is the obvious choice, unless you are the strongest in the server and you dont have any problems staying alive vs blitz teams during sage or matsurii- then you can mood him for nin.