Did you manage to knock out heroic mode Hagara? Wondering where to go next? The summoner of ooze, Yor'sahj should be next on your list. Perhaps the biggest change in heroic is the extra ooze that spawns that your raid needs to deal with. This means Yor'sahj has more abilities with which to assault your raid. This encounter doesn't exactly have a set script, since Yor'sahj cycles through different slime combinations.
For healing setups, I strongly advise bringing in no more than six healers. Healers will want to configure their UIs so that they can view Deep Corruption debuffs on their raid frames. All in all, Yor'sahj hinges heavily on the ability of your raid to react to the different combinations.