As a sl/sl and resto druid you should have a really easy time with this combo, you can just outlast them.
The warlock should just dot up the targets, kite around a little, and drain mana of the priest when possible, also fear alot.
You should basically just stay like "on the other side" of the warlock and rogue fighitng eachother than the priest. Whenever the priest runs to you, do travel form and run away. If he doesn't get close to you, he can't fear, and thus he have to stop and heal cause your warlocks dots are doing heavy damage.
Just cyclone the rogue if your warlock starts getting low, (which he almost never should), or the priest if the rogue is getting low. It can also be an idea to cyclone the rogue if there's an inc heal, since cyclone makes him immune to heals.
Just outrange/LOS the mana burns, and you should be easily able to outlast them.
Good luck!
