How we defeated Sartharion-10 with three drakes

First, please understand that this isn't intended to be a comprehensive guide to the fight.  This is why I don't write guides is a blog tag for a reason!

No, my intention here is simply to share how we defeated the single-hardest encounter in the game, and hopefully provide some insight into our strategy, thought processes and basic positioning to other groups looking to attempt it.

For the purposes of this discussion, I'm going to assume that anyone reading it is already familiar with the basics.  If not, WoWWiki is an excellent resource.  (Go!  Check it out.  I'll wait.)

Okay, then.  Very briefly:

• Sartharion is a typical dragon, in that he cleaves, breathes fire and tail swipes.  He has to be tanked throughout the encounter and will summon three Twilight Drakes at timed intervals.
• The Twilight Drakes are Tenebron, Shadron and Vesperon.  Like Sartharion, the Twilight Drakes drakes also have a breath attack, although theirs deal shadow damage rather than fire.  In addition, each drake (1) opens a portal to another realm and (2) has an aura that will remain active on the entire raid for as long as the drake is alive.
• Tenebron lands first, a mere 30 seconds into the fight, at the far west end of the island.  Her aura, the creatively-named Power of Tenebron, increases the amount of shadow damage taken by the raid by 100%.  She spawns eggs in the portal realm that hatch into Twilight Whelps, which must be picked up by the add tank.  Otherwise, Tenebron's portal can be safely ignored.
• Shadron lands 60 seconds seconds into the fight, towards the south end of the island.  His aura increases the amount of fire damage taken by the raid by 100%.  He also spawns an acolyte in the portal realm, who increases fire damage done by Sartharion by 50% and renders Sartharion immune to all damage.  For this reason, Shadron's acolyte is the only one we bother to kill.
• Vesperon lands 75 seconds into the fight, towards the north end of the island.  His aura reduces everyone's maximum health by 25%.  Like Shadron, Vesperon spawns an acolyte in the portal realm.  While his acolyte is active, Vesperon gains the Twilight Torment effect, which increases fire and shadow damage taken by 75% and reflects a percentage of all non-periodic damage done to Vesperon back onto the raid.
• In addition to Sartharion and the Twilight Drakes, there are several AoE effects to contend with: (1) a lava wave that sweeps across the island, and must be avoided; (2) lava strikes that target individual players, deal painful splash damage and spawn fire elementals; (3) the fire elementals themselves, which will become enraged if struck by a lava wave; and (4) void fissures summoned by the Twilight Drakes.
• When all three drakes are alive, Sartharion's breath and most AoE effects can one-shot the raid.  Cooldowns like Divine Guardian and Guardian Spirit are absolutely required to save a tank from a one-shot breath.

If it sounds like a lot to deal with at once — it is!  Once upon a time, a resto shaman of my acquaintance described the Illidari Council as the "Superbowl of Not Standing in Bad®" ...

Ha!  How naive and innocent we were back then!

Group Composition

We experimented with several different group compositions.  In the end, this was the winning combination:

Main Tank: Death Knight
Drake Tank: Feral Druid
Add Tank: Protection Warrior
MT Healer: Holy Paladin
Raid Healers: Holy Priest, Restoration Shaman
DPS: Elemental Shaman, Fire Mage, Mutilate Rogue, Shadow Priest

As you can see, it's a fairly straightforward, three tank/three healer/four DPS set-up.

As Ashellia noted, many of the strategies you'll find online recommend bootstrapping a hybrid to fill the role of two characters.  For several attempts, we tried having a healadin tank the fire elementals and Twilight Whelps by using Consecrate and Righteous Fury plus Flash of Light to keep himself up and hold healing aggro.  The idea was to replace our add tank with a fifth DPS class — preferably an unholy death knight, balance druid or affliction warlock for the +13% buff to magical damage.  Unfortunately, this put us at the fickle mercy of the RNG: if we caught a bad string of void zones or lava waves, then our multitasking paladin would be forced to concentrate more on dodging The Bad® and less on healing.  Lacking the mitigation and/or avoidance of a real tank, he would inevitably succumb and loose adds on the raid.

Switching to a three tank/three healer combination put considerable pressure on our DPS, but also gave us much better control over the fight and the fifteen hundred things (I'm not exaggerating: there really are that many — I counted!) that can go wrong.

A few things worth mentioning about this particular composition:

• Death knights have more panic buttons available to them than any of the other three tanking classes.  Using a death knight tank meant that we only had to coordinate two other cooldowns to survive what we came to refer to as Sartharion's "one-shot breath phase."
• Protection warriors make excellent add tanks!  It seems to me that many, many warriors are still locked into the old TBC mindset (i.e., that warriors are single-target tanks — period, dot — and paladins are the superior AoE tanks).  This is no longer the case.  Don't believe me?  Ask Spinks!
• Our priest was Discipline for our first few (dozen...) attempts.  At first blush, Grace and Pain Suppression seemed too good to pass up.  But we eventually came to realize that a combination of one single-target healer and two AoE healers was vastly superior to two single-target healers and one AoE healer, and so our priest donned wings for the occasion.
• Two shamans = two Bloodlusts!  This meant we had a Bloodlust available for every learning attempt.
• A rogue was the lone melee DPS in our caster-heavy raid.  (/tar Ignus /lick).  Not only was he expected to DPS the drakes and tank Shadron's acolyte during portal phases, but he was also tasked with tranquilizing enraged fire elementals.  The add tank pulled them to the rogue, and the rogue used anesthetic wound poison and Fan of Knives to great effect.
• (The downside of calling for fan of Fan of Knives is that it inspires the raid to make awful FoK puns all night.  Be warned.)
• Finally, having only four DPS meant that we had to eke every last bit of damage out of them.  To this end, our holy priest dusted off his Smite button and our bear tank learned how to dance!  (More on that, later...)

Safe Spots & Basic Positioning

Our Death Knight tanked Sartharion in the southeast corner of the island, alternating between the two "safe spots" marked (roughly!) in yellow.  His healer, a paladin, moved with him — running through Sarth to the easternmost tip of the island for waves originating from the north.  (I highly recommend running through Sarth rather than around him, as less movement = more healing, especially for an MT healer without instant casts.  Just be sure to stay closer to his forelegs than his hindlegs to avoid an untimely tail swipe.)

Meanwhile — and this is one of the keys to our success, because it maximized DPS time — our drake tank moved between three tanking postions, from (1) the western edge of the island, where Tenebron landed 30 seconds into the fight, to (2) the southwest corner, a south- wave safe zone, to (3) the center of the island's southern border, a north wave safe-zone as well as Shadron's landing point.

While Tenebron and Shadron were active, the raid spread out throughout the island's central band, in the north-wave safe zone.  For south waves, we ran west (away from the instance entrance).  The drake tank and melee DPS shifted west well.  Meanwhile, the Sarth tank and his healer alternated between the two eastern safe zones (closer to the instance entrance.)

The challenge with this positioning was that it frequently put the MT and MH out of range of the rest of the raid.  For this reason alone, it was absolutely critical that the healers trust each other to cover their respective assignments.  (I was going to elaborate on this point, but Bellwether published an excellent post on the subject this morning, so I'm going to direct you to her instead.)

Finally, once Tenebron and Shadron went down, the entire raid shifted east and alternated between the same safe zones as the MT and MH.

A Walk-Through

We started each attempt with our death knight on foot, and the rest of the raid mounted — or ghost wolf'd, for the sheer novelty of it. <insert wolfish grin here>

The death knight pulled Sartharion into position, closely followed by his healer.  At the same time, the raid road around Sarth (mindful of his tailswipe!) to the center of the island, a north-wave safe zone.  Although we weren't concerned about damaging Sartharion at this point, the drake and add tanks and lone rogue had 15-20 seconds to generate rage or combo points before Tenebron landed.

Twenty seconds into the fight, our raid leader called "Positions for Tenebron!" over Vent.  This was the cue for our drake tank and melee DPS to peel off of Sartharion and dash/sprint to the western edge of the island in preparation for Tenebron's landing.

Because he was already in position, our drake tank was able to pick up Tenebron the moment he became targetable and move her around the southwest corner of the island.  This in turn allowed DPS to unleash on her almost immediately, especially if we were lucky enough to catch a south wave.

We typically blew our Bloodlust at this point, with a goal of bursting Tenebron down before she could open a second portal and thus spawn a second wave of Twilight whelps.  Since raid damage relatively light this early in the fight, our holy priest was able to DPS (lolsmite?) until Shadron landed.

... I might've cast a Lightning Bolt or two, myself.  Don't tell my raid leader.  >.>

In preparation for Shadron's arrival, the drake tank moved Tenebron along the southern edge of the island, towards that central band/north-wave safe zone.  He tanked Shadron here when he landed, and fifteen seconds later pulled Vesperon to this location as well.  (In the 25-man version of OS, our drake tank typically drags Shadron to Vesperon's landing point and tanks both drakes on the north end of the island, but this strategy caused range issues for our healers in OS-10 so we abandoned it after a few attempts.)   The drakes were tanked on the southern edge of the island for the rest of the fight.

As soon as Tenebron went down, DPS switched to adds and AoE'd them down— providing some much welcome relief to our warrior tank, who by this point was holding at least one wave of Twilight whelps and all of the fire elementals spawned thus fars.

With the whelps slain and fire elementals back under control, DPS focused Shadron.

After Shadron died, DPS and one healer entered the portal realm to kill Shadron's acolyte, as Sartharion is immune to damage whenever Shadron's acolyte is active.  We ignored Vesperon's acolyte (we learned after one particularly heartbreaking wipe that killing both acolytes extends the fight unnecessarily and causes undue strain on healer mana), and simply exited the portal after Shadron's acolyte went down.

Since Vesperon's acolyte was alive (and ranting impotently) in the portal realm, the Twilight Torment remained active as DPS began the slow, controlled burn on Vesperon — backing off any time they dipped below 40% health.  By this point, the fight had long-since become a blur to me; between frantically dodging void fissures and lava waves, not to mention healing through constant AoE and reflective damage, I didn't even notice Vesperon die until I heard Keaton's perpetually calm voice reminding us not to panic, because this is the fight we've done a hundred times before.

With all three of the Twilight drakes down for the count, our bear tank taunted Sartharion and took over as MT and our death knight switched over to DPS.  At this point, the fight became the simple tank 'n' spank ('n dodge The Bad®!) that we all know so well.  The only difference was that we did it while holding our breaths, because victory was seconds away ... and history tells us that's usually when something goes disastrously wrong!

Fortunately — this time — it didn't.

Tips

Some final comments and tips from our experience:

• Don't worry about DPSing Sartharion in the 30 second window before Tenebron lands.  First, it isn't necessary.  Second, your MT will probably be in stamina gear, and won't have the hit or the swift threat generation you're accustomed to this early into the fight.  Feral druids, warriors and rogues can take a swipe or two (no pun intended!) at Sarth to build rage or combo points, but everyone else should use this time to get situated: drop your totems or Demonic Circle, familiarize yourself with the safe zones, cast a Riptide on the MT to proc Tidal Waves, etc.
• The drake tank and melee DPS should already be in position when Tenebron lands.
• If raid DPS is a little low (and ours was, with only "four" real DPS and a Smite-spamming priest), use Bloodlust/Heroism to burst Tenebron down as quickly as possible.  If he lives long enough to summon a second wave of Twilight whelps, then your add tank can become overwhelmed.
• Coordinate your tank-saving cooldowns before the fight, and have someone call for each cooldown in a pre-determined order.  If you're in the cooldown rotation, this is your #1 priority; with all three drakes in play, Sartharion can and will one-shot the tank.  Communication is key, not only to ensure that no one misses a cooldown, but to cover other raid roles as well.  (For example, when it was our holy priest's turn to use his cooldown, our elemental shaman assisted with raid heals.)
• You don't need a plate DPS class to tank Shadron's acolyte in the portal realm.  Our rogue did it, and was very easy to heal.
• Have someone who isn't in the portal realm call lava waves on Vent.  If a lava wave is active or imminent, wait until it passes to exit the portal.
• Play to your strengths. Don't feel trapped by someone else's strategy; assess your strengths — and weaknesses — and adjust accordingly.
• Don't get discouraged! This is the hardest fight in the game, and you're meant to wipe on it ... a lot.  It took us close to 20 hours of attempts over the course of several weeks to learn.  Progress can be agonizingly slow and is often difficult to measure, especially because there are so many random elements to overcome.  It isn't unusual to down two and half drakes in one solid attempt... and then wipe in the first thirty seconds of the next one because your drake tank found himself trapped between a void fissures and a lava wave or your holy priest ate two successive lava strikes.  As frustrating as this encounter can be, it is the cumulative challenge of all these rage-inducing elements that makes the eventual victory worthwhile.  Believe me, triumph is sweet ... and it tastes like dragon.