User blog comment:ClariS/Why Xerath's Passive is Bad/@comment-4929329-20130317232050/@comment-4929329-20130318221220

It takes a fraction of a second to get sucked into a teamfight, and if you stay at ~1100 range, you will not get your stun off on a target that it would be useful on. (ADC, ranged AP)

You make it sound as though Xerath starts the game with the cooldown reduction to relocate over and over, and that enemies cannot possibly reach him, yet Lux gets caught often enough, and she has more mobility and ways to escape than Xerath does. Additionally, you assume that split second decisions do not change games when you dismiss the cooldown that Xerath's root has, which is completely false. Most champions in a teamfight tend to die around 4 seconds of focus fire (tanks can take up to 12 or so) if they are okay on farm) but those numbers are pushing it. If you get so much as silenced, the enemy team can find and kill your bruiser, then your support, before you are done relocating. As Xerath, threat (of damage) is almost literally all you are.

Enemies will run, but staying a little closer means you can use the Mage Chains + Arcanopulse to stun their initiator and hit their team, then ult their team, since the tank is seperated from his team. If Talon leaps on you? Well, that is why I build more durability on Xerath, but I would never consider buying a full tank item.