User blog comment:ClariS/Why Xerath's Passive is Bad/@comment-99.55.245.182-20130317160736/@comment-99.55.245.182-20130318141425

If you're someone who excels at launching long range missiles, would you want to use Zhonya's? The active is wasted on someone like Xerath.

Other long range mages often will have some other forms of defense besides building just AP items like Xerath often does. He needs some form of stability. Otherwise, he'd always get knocked out with one hit by pretty much any ADC, or even many AD bruisers.

Ryze is a mid range caster, but you build armor and MR on him. Annie can be built like a magetank. I usually do build Zhonya's on Fiddle or Swain, so I can keep their ult up and not take extra damage. Same goes for Malzahar. I build Morgana pretty HP heavy, and depending on team comp, get Tabis.

Xerath needs some form of defense since getting a Zhonya's, the only AP/Armor item out there (except armguard, which would work for early-mid game, but not late), is a waste of a slot.