The king can not fight Magis alone even if magis has a very small army because that small amount of damage is enough to let Magis survive with low health . But you cant support the king because Magis can make them disappear with 1 spell . That dont want to die ability hurts you more , because the AI only really has few swords and spears that die quick then Magis is the only front unit but with the ability he can survive , your spears die because the electric walls , you see most his stuff is dead so you try to kill him with king , the small army he has helps him survive , then you get unlucky and most your army dies.