My understanding of how resist works is fire-based spells check against your fire
resist (like DryBoneFireBurst, Ignite), cold-based spells against cold (Frost
Spiral of Al'kabor, Shock of Frost), and the rest fall under Magic (such as Force
Shock, GhoulRoot, Knockback, MortDrowsy, Sanity Warp, Charm, Lightning, etc...).
I also think poison-based DOTs check against Poison resist, because I got two
silver-plated bracers which put my base poison resist at 30. I have never resisted
a poison-based DOT previously, and now if it is cast by a blue or green con I seem
to resist it every single time.

I was surprised someone asked what the value of Elemental and Guardian were. If
you ever go to Unrest and plan to fight hags, use them. For my party it makes the
difference between everyone finishing the battle having lost a half-bubble of
health, and losing 2-3 bubbles. It seems to be particularly important against the
hags DD spells, lightning and Shock of Force. Her primary AoE is the Frost Spiral
of Al'kabor. How do I know? Because I usually get the resist message for force
shock, and occassionally get it for Frost Spiral. I also think the chance of
resisting is weighed against either your level or your defense skill, because
anyone who has been to Unrest at level 20 and tangled with a hag died in 2-3
spells, while a L30 takes quite a beating before dying.

Ariell Thunderwolf, Karana