What you do is drive the ra'zac towards saphira by pressing 'y' or 'x' whilst facing the way you want the ra'zac to go. Make sure you are near enough to the ra'zac otherwise it will not move. It will do a backflip away from you in the direction you faced. When you have made it move you must get back in front of it as quickly as you can otherwise it will dodge you and run away again. Do not stand still for too long or else it will attack you, so pause the game by pressing start if you need a break. When it is near enough to Saphira she will knock the ra'zac to the ground. Keep doing this until it dies. This may take a while, but perservere and you will make it eventually. Good luck!!

all you need to do is run around and then when he stops just hit it but not for too long
on it can kill you.