The first miniboss is easy, I think I use only 1 earth elemental (I have 5 shammy though). The second one is kinda a bitch though, make sure to purge shadow power (well do the same for the first one too) and move away when he raises his arms. At that point your earth elemental will probably be killed so lay another one down when he drops his arms. I say wait till after Arm Raise to drop fire elemental totems which will really help if one of your guys has died. You should probably be able to do it with 4.