
So, installment number two of my 25 man healing guide ^.^ (If you missed it, I did do a review of Gruul’s not to long ago ^.^)
There’s tons of guides out there for this fight. To name a few:
Bosskillers
WoWwiki
MMO Champion
You get the idea. Many people out there who can give you a general feel for the fight.
Here’s what it’s like to heal it as a lil’ ol’ priesty.
Bear with the diagrams… they’re the best I can manage without my tablet (the mouse is busted T.T)
So! … I just hit save, and it like, looked like this thing was published… ok, it’s a bad idea to write my post at 3am… but ITS IN MY HEAD NOW!
Anyway. Keep in mind, others may do this differently, but here’s what we’ve done in AC for sometime and it seems to work ^.^

This is the staging area for Hydross. The general composition for such a fight is going usually as follows:
Frost Phase Tank, Nature Phase Tank, 1(Pally) and 2 other Add tanks, 5 to 8 healers, DPS (AoE’rs like Locks, Mages, 1 minute Boomkin)
Healing wise, you have two groups: Phase tanks, and Add tanks. The Phase tanks will take more damage the longer they’re tanking Hydross on one side of the Magic Line (more on the in a sec.) The Add tanks won’t need healing until the first Transition. Usually, I have a Pally, a Tree and a Priest on the phase tanks, and whoever is left gets Add duty. Also, keep a Renew handy for the people who get caught in Water Tombs (more on that in a sec.)
The Frost Resist tank is the first up to bat, and usually the start of a pull will look like so:

The little push over adds that spawn from the side are pretty much a rage cookie for your Frost tank. Let him/her get the rage they need, while the melee take care of whatever keeps getting spit out. Once your Frost tank is good to go, he/she will go on in and engage Hydross.

So, the whole raid is now kicking Hydross butt. Everyone is on the side of the line Hydross is on. (I know, Nature tank “isn’t” but pretend s/he is there for now.) If Hydross happens to cross that Magic line before the raid is ready, her adds spawn and there is a strong possibility of imminent wipeage, since the first reaction of someone who pulls aggro is OH SH!T, and then using their aggro wiping ability, which makes Hydross RECROSS the Magic line, thus spawning even MORE adds.
So yea. It’s bad.
During each phase, Hydross will do a raid wide “Mark”. This increases the Frost/Nature damage the raid receives by a certain percentage (25/50/100/200 respectively). This is why the Phase tank will start taking more damage. The Marks are timed, and usually, 5 seconds before the 3rd Mark, we call for a STOP to DoTs (and usually HoTs, so no Renews) and for the Nature phase tank to get ready to tank. This is when it’s OK to cross the line… but do so with caution. In Frost Phase, Hyrdross does a Water Tomb attack that will encase you and anyone within 5 feet of you in a globe of water that stuns you and does frost damage over time to you. It’s never good to have a clump of people (especially if it’s your Nature/Add tanks) stuck in a Tomb when the Frost tank is bringing Hydross over the line. So make sure you watch out. The stun also only lasts for about 3 to 5 seconds too.
At the 4th Mark, the Frost tank starts bringing Hydross across the line and POOF! We have adds!

Hydross is not happy. You’ve taken her out of her nice clean sanctuary and now she’s got to like, I dunno, breathe Naga farts. So she’s poisoned and now inflicting Nature Marks to the raid. Oh and she brought some friends, so you have 4 aspected Adds looking to fight. Nature phase’s “Water Tomb” is a small DoT that lowers effective healing. Honestly, I really have never noticed the reduction in healing in this phase. It’s the lesser of the two evils when it comes to the random attack Hydross does. Renew and forget (which you will, because there’s no visual to this attack like there is with Water Tomb.)
Now, as for the Adds. The way we do it, pally tank drops his consecrate as soon as they spawn, Hydross is Misdirected onto the Nature Tank so that that little UMPH of threat gives him/her a chance, and then any stray adds are picked up by the two half and half resist tanks to bring back to the pally. Once the Add tanks have their mobs, AoE commences. (Some guilds do a single target DPS to kill them and it works, but we AoE with seeds and arcane explosions.)
Watch the locks health, and bubble those mages. Pallys are AMAZING AoE tanks, but squishys are squishys, and they might need a bubble or heal to keep them alive. The Add tanks might also take some initial spike damage from a Hydross hit too, since they’re trying to establish aggro so quick, so if you’re an Add tank healer, be ready for it.
By the second Mark, the adds should be down, and it’s back to killing Hydross. When the 3rd Mark comes, the Frost Phase tank and the Add tanks should be ready on the other side of the line for the Transition.

This time, there’s Frost Adds instead of Nature Adds, but the strategy is the same. I usually find it easiest to heal AT the line, spread out so that not all the healers get nailed if we get Tombed. That way, you have the least amount of distance to run in case of emergency.
Some things to note: Circle of Healing (LoLCircle) works very well for everyone here. There is very little room to maneuver, and while there are spots you can stay and not be doomed to get chain Tombed, everyone is still within spitting distance of each other and a LoLcircle on a ranged for an AoE heal won’t necessarily be wasted. Fribee (Prayer of Mending) for your tanks is a god send because, (and I think I forgot to mention this earlier) each transition phase is an aggro wipe. This is why you want to try and refrain from HoTs around Marks 3 and 4. Though, if you DO happen to pull aggro, Shield and run to the center! Make a Bee line for your Add tanks, and they should be more than happy to peal the angry mob off you.
So, what do you have to look forward too once you’ve downed Hydross? The healing priest has the Wraps of Purifcation. They are pretty fun, at least till you can get the ones off of Rage Winterchill. ^.^
Next time, at SSC camp, we’ll talk about my Favorite Fight: the Lurker Below!