Ive been talking this over in the IRC channel with some people.. There are two different views, one is to cover all of your bases. Make a diverse enough team that can give you pretty much everything just be prepared to deal with the complexity that this can add in. Second option is to have a team made up of mostly shamans with one or two other supporting characters. If you take a DK as the tank and go Unholy you can get the Ebon plague which has the 13% increase to magic damage for your ele shamans. If you take a pally tank you might want to then consider swapping out one of the shamans for a warlock for its CoE along with its dot based DPS and such. A secondary tank option was that of a well geared Druid. Apparently an under geared druid can be a bit too hard to heal.