User blog comment:ClariS/Why Xerath's Passive is Bad/@comment-173.189.222.243-20130317133247/@comment-4881935-20130317164143

@ OP, if the enemy managed to reach you, you realize that the enemy is completely alone, meaning your teammates should easily surround him and murder him.

And your W grants bonus movement speed, allowing you to re-position with him. If that Matheon manages to wait it out the teamfight to first locate you, and then charge it, all while you aren't moving, then he deserves to reach you. But with your range, everyone else shouldn't be ale to reach you unless they tank through your entire team.