Those are the rock guys before the 2nd boss, and you are right train a bunch up 3/4ths of the way thru the stairs (no healing, earth shields, etc) and then kill one at a time healing after each one dies.

For the nature guys just use flame shock/lava burst/etc liberally, its a bit painful. I kill the big elemental one first, then the little ones, then the revenant. They are immune to nature damage so you have to use fire/frost instead. Ionar herself is NOT immune to nature damage so everything works fine there.

BTW Onyxia is immune to fire damage iirc so if you go back and do her put only lightning bolt in your spam button