Mordenkainen's Disjunction - so you've been playing your wizard from 1st to 17th level. You are intricately tied into several world spanning plots. You cast a spell and accidently catch an artifact in the AoE. You roll badly. You can't cast spells ever again. At a minimum, the artifact clause in MD should require that you are consciously trying to destroy said artifact when you cast the spell.
(Okay, it only happened once but I can't imagine complaining about entangle or web. I like a high magic game.)