relatively low saves = relatively high hit dam = trouble for shaman anyway 
Deteriorate
well my rule of thumb is when I see deteriorate on my affected list of spells I don't stay in the fight. In fact I will purposely dance around wildly untill it has gone away. This is one spell I do not stay to chat with if you know what I mean.
There are other battle tactics to get around deteriorate. You simply have to be crafty.
Like one-rounding the shaman so he can't land it?
that wouldn't hurt
As a big fan of the all out offense, I like that tactic alot. But for those people who are a bit more balanced in their approach, there are ways around deteriorate that I won't get into here, but you just have to think about what it does and how you can manipulate it.
Your giving it away already Grish!! Not that its hard to work out if you think of how the spell works
I think somebody already talked about it in a different thread. Mya said to have two sets of eq, one hit/dam until they land it, then switch in your mal set. Something like that. Although I suppose that's giving "it" away.
Thats common sense, har har when I started this post I was just poking fun at how its an oxymoron of a spell.
I one rounded Jesiana on Fisuh. It was a challenge, too: It was so fast, my mammoth didn't initiate until after she was kneeling, and killed her.
Har.
Warmaster + Feral + Dual weilding = not surpised.