Are you talking about Ionar, that wind elemental that splits up into little lightning "spiders"? She is not immune to nature damage, just a lot of the trash before her is. My main dps button does a /castrandom lava burst,lightning bolt, plus I have a mage so it takes a little longer to take down the trash but its not too bad. For the boss, there are a few strats on this forum, but basically just put everyone in a seperate corner in the room before her, drop healing stream totems, and just heal up whoever is taking lots of damage when she splits up. You have to keep people away from each other so they don't spread the damage, and you have to heal up anyone who is currently taking lots of damage. A NR totem helps a lot of course.