[B0rsuk]

And I don't like the idea. Not just because it's s cliche. I prefer when school strenghts come from gameplay mechanics, and not from artificial bonuses. Besides, there are some spells with odd path combinations, like acid spells (fire + water, nature + death ). They are possible because no two schools - so far - are directly opposite to each other. Nothing is set in stone.
Anyway, spells designed to fight certain paths already exist, even if they're not very numerous. Kindly Ones, Maggots, Cleansing Water, Inner Fire, Purgatory, Astral Corruption, Rain; spells that affect climate upset either fire or water mages. Wind Ride is ineffective against Earth mages. Lots of suble and less subtle effects.