Hydross The Unstable
This is the first boss of Serpentshrine Cavern. Visually the raid can see both Hydross the Unstable and The Lurker Below from the entrance. Directions to Hydross are not necessary since the raid can see him. Clear the ramps to Hydross and skirt the raid around the edge of the circular platform where Hydross is standing.
Abilities
Hydross is an elemental with 3,500,000 hit points that changes forms during the fight. Hydross enrages after 10 minutes.
Poison Form
While in this form, Hydross melee hits do nature damage and is immune to nature spells. To switch Hydross into Poison Form, pull Hydross towards the edge of the platform, before the two beam columns.
Mark of Corruption: Hydross places this debuff on the entire raid. It stacks up to 6 times, steadily increasing the amount of nature damage taken by the raid by 10, 25, 50, 100, 250 and 500 percent.
Summon Elementals: Hydross summons 4 nature elementals when switching into Poison Form. Each Elemental is immune to nature damage and does nature damage to targets. They have 60,000 hit points and melees for 6,000 nature damage per hit.
Vile Sludge: Hydross casts this spell on a single target every 15 seconds. It reduces healing and damage done by 50 percent and places a DoT on the player that does 4,000 nature damage to the player over 24 seconds.
Water Form
While in this form, Hydross melee hits do frost damage and is immune to frost damage. Move Hydross to the back of stage into the beams to switch him into his Water Form.
Mark of Hydross: Hydross places this debuff on the entire raid. It stacks up to 6 times, steadily increasing the amount of frost damage taken by the raid by 10, 25, 50, 100, 250 and 500 percent.
Purify Elemental: When Hydross switches into Water Form, he gains this buff from standing in the water beams.

Summon Elementals: Hydross summons 4 water elementals when switching into Water Form. Each Elemental is immune to frost damage and does frost damage to targets. They have 50,000 hit points and melees players for roughly 6,000 frost damage.
Water Tomb: Every 7 seconds, Hydross casts this spell on a single player. The player is encased in a large bubble, stunned for 4 seconds, and hit with 4,500 frost damage over a period of 5 seconds. All players within 8 yards of the affected player receive a Water Tomb a well. This is especially dangerous for melee damage dealers. At least two healers should be assigned to healing the players that are affected by Water Tombs. Try to position one healer on either side of the raid so that no one is out of healing range.
The Pull and Position
While on the ramp leading to Hydross’ platform, the raid will see an assembly line of elementals spawning from the right. Slowly inch the raid over to the right, staying near the edge of the platform. Clear the adds, being careful not to aggro Hydross. The further to the right the raid goes, the closer the raid can get. While finishing up the last elemental, the first tank runs into Hydross. If the raid wants to keep in Water Form, the frost tank should run into Hydross using an Invisibility potion and using the Bloodrage ability. This is the easiest method for the initial pull. Once Hydross is engaged, the healers and the rest of the raid follow the frost tank.
The Hydross tank healers can remain on the ramp so they are able to get into range quickly when the tank engages Hydross. It is important to not that this top ramp area is also the wipe recovery spot.
Battle
Since Hydross switches forms, have two tanks specifically for Hydross: one for each form. Each tank should have resistance gear on designed to resist a fair amount of the damage of the specific form. Besides the two Hydross tanks, there should be at least two elemental tanks. These tanks need to wear a mixture of frost and nature resistance gear. These tanks can be warriors, paladins, or druids. All three classes are able to effectively tank the elementals.
Instead of talking phases, this description discusses forms since each of the two phases is actually based on Hydross’ forms. To switch between forms, use the two flags on either side of the platform as the trigger form

indicators. Pull Hydross down the incline, across the invisible flag line to start the Poison From. Pull Hydross back to his original position near the back of the platform to return Hydross to his purified or Water Form.
Aggro sensitive ranged healers and damage dealers must adjust positions between phases. At the end of the first form, the boss needs to be at 80 percent. Each subsequent form lasts about 1 minute before needed a transition.
Hydross’ Purified Water Form
Hydross is tanked near his original spawn spot. When pulling from the Poison Form to the Water Form, the nature resistance backs Hydross up the slight incline, over the trigger line. As soon as the nature resistance tank moves Hydross over the trigger line, the frost resistance tank should Shield Slam and Heroic Strike once Hydross changes colors to gain aggro. Instead of waiting until later, the frost tank should reposition Hydross by turning so that when it comes time to drag Hydross over the trigger line, he or she only needs to back up.
As the phase continues, Hydross summons spawns that are addressed later in this section. Hydross casts Water Tombs during this phase on random raid targets. The raid must be spread out to avoid chaining Water Tombs throughout the raid. Meanwhile the Mark of Hydross that is on all raid members steadily increases. When the Mark of Hydross stacks so that all raid members are taking 100 percent frost damage, the tank should start getting ready to move Hydross over the trigger line. The tank should give damage dealers a 15 or 10 second warning before dragging Hydross over the trigger line. At 5 seconds, the tank drags Hydross over the trigger line to start the form.
Damage dealers need to back off damaging Hydross during this transition. The frost tank is only maintaining the aggro on Hydross, not building it. A helpful tip for ranged damage dealers that may pull aggro is to move to the nature side while Hydross is in his Water Form so that if they happen to pull aggro during the transition, Hydross will be already on the correct side and easily picked up by the nature tank. If the transition is successful, damage dealers can resume damaging Hydross after 5 seconds after the tank switch occurs.

Healers need to pay special attention to the Water Tomb players. There are game modifications such as Grid that allow healers to input special curses or magical effects to show up on player targets. As the Mark of Hydross increases in strength, these players are going to need more healing. The main tank healers should follow the movement suggestion for the damage dealers in the previous paragraph. Unlike the damage dealers, healers may not be able to back off healing the tanks and may rip aggro during the transition. Realizing this, they should start moving during the frost phase so that the main tank healers are on the poison side of the trigger line. Try to make sure that not all of them are moving at once. During the initial phase, it is easy for healers since they come into the fight after the tank and can be on the poison side.
Hydross’ Poison Form
When it is time to move Hydross into his Poison Form, the nature resistance tank should be near the center of the bottom of the stage ramp (the decline makes an arrowhead design and tank should stand near the arrowhead). Tank Hydross at the center point where the incline and platform meet. As soon as the frost resistance tank moves Hydross over the trigger line, the nature resistance tank should Shield Slam and Heroic Strike once Hydross changes colors to gain aggro. Instead of waiting until later, the nature tank should reposition Hydross by turning so that when it comes time to drag Hydross over the trigger line, he or she only needs to back up.
As the phase continues, Hydross summons spawns that are addressed later in this section. Hydross casts Vile Sludge during this phase on random raid targets. Meanwhile the Mark of Corruption that is on all raid members steadily increases. When the Mark of Corruption stacks so that all raid members are taking 100 percent nature damage, the tank should start getting ready to move Hydross over the trigger line. The tank should give damage dealers a 15 or 10 second warning before dragging Hydross over the trigger line. At 5 seconds, the tank drags Hydross over the trigger line to start the form.

Damage dealers need to back off damaging Hydross during this transition. The nature tank is only maintaining the aggro on Hydross, not building it. A helpful tip for ranged damage dealers that may pull aggro is to move to the frost side while Hydross is in his Poison Form so that if they happen to pull aggro during the transition, Hydross will be already on the correct side and easily

picked up by the nature tank. If the transition is successful, damage dealers can resume damaging Hydross after 5 seconds after the tank switch occurs.
Healers need to pay special attention to players with the Vile Sludge Dot on them. As the Mark of Corruption increases in strength, these players are going to need more healing. The main tank healers should follow the movement suggestion for the damage dealers in the previous paragraph. Unlike the damage dealers, healers may not be able to back off healing the tanks and may rip aggro during the transition. Realizing this, they should start moving to the frost side while Hydross is in his Poison Form. Try to make sure that not all of them are moving at once.
Elemental Control
At least two tanks are needed to control the elementals. They should have a combination of both frost and nature resistance gear. Many guilds use warlocks to Banish the two back elementals while the two warriors tank the front elementals. Try to keep the tanked elementals near Hydross. While keeping at least 2 rogues on Hydross, place the others on the adds. If damage per second on the adds becomes an issue, have each of the tanks double-tank the adds. Healing may become more intensive but if healers, the elemental tanks, and rogues communicate well, healing should not be a problem. Rogues and tanks can use their abilities to stun the adds and decrease damage taken by tanks if their health drops too low. Warlocks should use their Seed of Corruption spells to damage the elementals and Hydross simultaneously. Mages can use Frost Novas to help control the positions of the elementals.
The first time Hydross is engaged, he will not spawn elementals until he changes forms then elementals spawn every form change. Continue handling the elements throughout the form changes until Hydross’ health reaches 15 percent. At that point, control the adds by fearing, bashing, using frost novas. Do whatever you can to kill to focus on killing Hydross. Pop all special trinkets and abilities to kill Hydross. If the raid does not make the enrage timer, the tank should Shield Wall to try to finish the fight. If the tank dies, the raid has the time it takes for Hydross to walk around killing raid members to kill him.