This works on both Normal/Heroic.
If you are doing this fight, your probably know they don't like debuffers or dispellers. In order to give your team a 30-50 seconds advantage, get your warrior to charge in and SPAM Demo Shout. Druid shout works as well.
He will be able to tank all the dper's for 30-50 seconds which should be enough for your raid to kill the healers.