The nature immunes are almost all individually pullable. I went into RFC at level 11 and found it very doable with melee+flametongue weapon and some fire nova totems if mana allowed for it.

As I leveled up, I found that melee was a very integral part of shammy boxing until about level 40+, it wasn't until then that melee started to become more of an annoyence then a help. Until 40 however, mana pools and regens just didn't seem to cut it and melee could mean the world of difference. :P