The big thing in this fight is your opener. Druids are unable to dispel, so I'll Seduce their partner, use Curse of Elements then usually start up a Soul-Fire or Chaos Bolt, all the while my Mage partner begins to get ready to shatter him. Soul-Fire will probably become less viable to use against suspecting teams, but I have gotten it off plenty of times against teams with Druids.

The one thing to look out for is that you do not have your mages Polymorph CC against Druids, but you still have Improved Counterspell and Deep Freeze. You'll want to be ready to instantly focus seduce the druid (if hes in caster) or ready to Shadowfury banish (if hes in tree). Once you have reached the DR limit on your CC your Mage needs to take over with what little he has.

In more cases than not that opener coupled with your instant CC on the Druid when he pops out will end the match fast.

Again however with Hunters, Death Coil is best used offensively on the Hunter, and not the Druid.

If the Druid decides to preemptively drop HoTs on his partner in Tree Form you can still go about your opener in the same way, just be ready to CC via Shadowfury/Death Coil-> Banish.

Mage PoV:

Your Warlock should start off with a Seduce on the Hunter which will allow you to open up with a shatter on the Hunter. Try to get a Deep Freeze up on the Hunter right away also. You can't Sheep the Druid, so your Warlock is doing the CC here for the most part, however if the fight goes on long enough you will need to throw a Counterspell and Deep freeze on the Druid to help out on CC.