User blog comment:ClariS/Why Xerath's Passive is Bad/@comment-99.55.245.182-20130317160736/@comment-4881935-20130319143610

because you will eventually get jumped. No champion is untouchable. Every champion should consider getting at least 1 defense item so they don't melt by one measly attack.

Zhonyas is just hands down the best defense item in the game, especially for casters who depends on their abilities.