Healing Assignments
Tanks:
There are two main tanks for this fight, one with frost resist gear and one with nature resist gear. They will pass Hydross to each other every minute or so. These two tanks get hit hard! So be sure to have at least 3 healers assigned to tank healing, preferably one with healing over times (hots) such as druids and priests and the others direct healers such as paladins. All three should be focused on keeping the two tanks alive.
Raid:
The other healers, should all be focused on raid healing. Randomly targetted raid members will take damage, maybe 3 members at a time, so you should be on the look out for these and be ready with heals for them. It appears as a bubble of blue or green around the player so it’s fairly obvious who is being affected. It only lasts for a few seconds so just be sure to keep them topped up.
The Frost and Nature Transition
There is the upper (frost) “platform” and the lower (nature) “platform”. When Hydross is passed between the two tanks over these two platforms, hydross changes between his frost and nature forms. Everytime this happens there is an aggro reset and 4 new adds will spawn. Usually the raid will stop dps’ing until the new tank has an aggro lead.
You don’t have to, but generally I like to be on the same platform as the boss, Hydross, when I heal. Simply because if I draw aggro by healing during this aggro reset/hydross transition stage, I won’t accidentally force Hydross to come chasing me to the other platform, hence causing Hydross to change forms again and thus spawning another 4 adds. So I recommend standing to the side out of the way and following Hydross to each platform everytime he is transitioned.
During each transition, any healer that has hots should put them on both tanks. This avoids casting huge heals on either tank during the aggro reset which reduces the chance that you will gain aggro. Be wary though, because the tank who is gaining Hydross will take lots of damage, so you may need to use larger heals anyway depending on how many hots you have on the tank.
Raid healers should be ready when the 4 adds arrive after every transition since the 4 adds will probably be tanked seperately by 4 off-tanks who will take damage from the adds. So make sure you conserve mana before the transitions happen.