You can only take one ward save at any one time, and ward saves do not combine - however, you are allowed to have multiple ward saves, and use the most applicable.
In this case, the wild riders use their 5+ forest spirit save against non-magical attacks, and their 6+ talismanic tatoos save against magical ones.
It's a shame you're stuck with a 'rules lawyer' as a regular opponent - I'll see if I can find a specific place(s) in the rule book which you can refer him to.
Edit: The paragraph in question is on page 30 of the main rule book (I don't know whether the little booklet is the same page-wise). The last paragraph under 'Ward Saves' states:
"...No model can ever try to make more than one ward save against a wound it has suffered. If a model has two saves for any reason, use the better ward save."
I hope that's helpful!
Servant of Isha.
This post has been edited by Servant of Isha on Aug 17 2007, 12:32 AM