I see what you're saying. But saying that it's pointless getting saves because deteriorate negates some of those saves is ridiculous, because things would be even worse for you if they landed deteriorate whilst you had no saves in the first place.
You can't compare a shaman with an invoker because they both have completely different playstyles.
The answer to getting around deteriorate? Depends on the class (and the race) that you play. It might be that you need more mal saves so that you can last that moment longer to outdamage them. It might be that you need better hit/dam so that you can dish out the pain.
Fact is, that you are right that a class with awesome saves is going to be a very tricky customer for any mage. But a shaman has ways of reducing awesome saves in a couple of ways, so that they can land their maledictions. Although it is meant to be tricky for mages to fight people with awesome saves, it shouldn't be impossible. Hence, why there is more to fighting a shaman that just having brilliant saves. Just like how somebody with awesome afflictive saves fighting an invoker could have their sanctuary dispelled (if they've sacrificed -mental for truly awesome afflictive savse) for improved damage from the 'voker, or if they're very lucky, destroy key pieces of EQ with hellstream. Just like when everyone complains when minister lands after a couple of tries against -400 mental saves, yet not that many people have had it click in their minds that instead of sacrificing everything for awesome mental saves, when the spell will land eventually anyway, focus on negating their ONE main damaging spell and it's affects.
Dey