Neato on the contingency tricks, it's just that kind of cheese doesn't suit my playstyle. No grief on anyone who wants to use them.
I'd say Contingiency is totally legit. Enemies use them too. Hell, how do you think dragons, or boss mages get their buffs out so fast? Contingiencies.
Contingency is legit, but getting the buffs out so fast just to see them get knocked down makes basic Contingency a poor choice (IMO) for a sorcerer spell slot. There's just way too much goodness at level 6, all of which can help you survive either defensively (stronger spell) or by killing the bad guys faster. And if the sorcerer is wearing the Robe of Vecna, a lot of those spells will be instant or near-instant cast, so you're at minimal risk of spell failure, which is the key reason to use a contingency spell in the first place.
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I agree with GamingFreak that contingencies are legit because, well....mages