Overview
There are four trash encounters preceding Hydross the Unstable. All mobs associated with the encounters will respawn two hours after being killed as long as Hydross is alive. Once Hydross has been killed, they will stop respawning, and any mobs that are still alive will despawn after the next soft reset of the instance.
There are two pack types: Tamer Packs and the Underbog Colossus. Once this trash is dead, you may attempt Hydross the Unstable or proceed to clearing the trash that precedes The Lurker Below.
Pack Order
Pack #1: Tamer Pack (1 Coilfang Beast-Tamer, 2 Coilfang Hate-Screamers, 2 Serpentshrine Sporebats)
Pack #2: Underbog Colossus (1)
Pack #3: Tamer Pack (Same as #1)
Pack #4: Tamer Pack (Same as #1)
Tamer Packs
Abilities
Coilfang Beast-Tamer
HP: 250,000
Immune to Crowd Control
Melee: Hits for moderate to high damage on plate.
Cleave: Deals physical damage to all targets immediately in front of the Beast-Tamer.
Bestial Wrath: Causes Serpentshrine Sporebats within 40 yards to enrage temporarily, doing additional damage and becoming immune to crowd control.
Coilfang Hate-Screamer
HP: 140,000
Immune to Crowd Control, Curse of Tongues
Melee: Hits for light to moderate damage on plate.
Silence: Periodically afflicts all targets within 30 yards of the Hate-Screamer with Silence for 4 seconds.
Arcane Blast: Periodically shoots an Arcane Blast at a random member of the raid, dealing 5k damage to the target and anybody else in the path of the Blast.
Serpentshrine Sporebat
HP: 130,000
Immune to Crowd Control unless Bestial Wrath is present
Melee:Hits for light damage on plate.
Charge:Periodically charges any target that is more than 6 yards away, dealing 2,500 damage.
Spore Burst:Periodically will afflict a member of the raid with an undispellable DoT that deals nature damage.
Assignment Macros
/rw – INCOMING TRASH ASSIGNMENTS –
/raid SKULL – Tank #1 (Coilfang Beast-Tamer)
/raid X – Tank #2 (Coilfang Hate-Screamer #1)
/raid SQUARE – Tank #3 (Coilfang-Hate Screamer #2)
/raid TRIANGLE – Mage Polymorph #1 + Tank #4 (Serpentshrine Sporebat #1)
/raid MOON – Mage Polymorph #2 + Tank #4 (Serpentshrine Sporebat #2)
Encounter Notes
Tanks A tank is assigned to each of the three naga. A fourth tank is assigned to acquire aggro on both of the Serpentshrine Sporebats. All tanks should enter combat and acquire their targets simultaneously.
Shortly after the Coilfang Beast-Tamer dies, the Sporebats’ enrage will fade. At this time the fourth tank should stop attacking the Sporebats, as they may now be Polymorphed by the Mages, reducing the overall damage output of the encounter.
DPS Kill the Skull (Beast-Tamer) first, followed by the X and Square (Hate-Screamers), followed by the Triangle and Moon (Sporebats). Always focus fire one mob at a time.
Mage Two mages will be assigned to Polymorph duty. After killing the Beast-Tamer, watch your assigned Sporebat; when enrage fades from the Sporebat, Polymorph it and continue to reapply Polymorph every few seconds in case of heartbeat resists. Continue Polymorphing until DPS focus fires your target, then resume nuking.
Underbog Colossus
Abilities
Melee: Hits for heavy damage on plate.
Special Abilities: The Colossus will possess one of the three following sets of abilities, determined randomly when it’s aggro’ed:
Type 1:
Rampant Infection: A Poison DoT that periodically afflicts a member of the raid, dealing 3,000 damage then jumping to another target. The Poison may be removed by any normal means.
Spore Quake: The Colossus will occasionally channel this ability, dealing 2,000 nature damage and causing a knockdown every tick over 12 seconds to everyone within 30 yards.
Type 2:
Acid Geyser: Periodically targets a random member of the raid and shoots nature damage in a wide cone at the target, dealing 2,000 per tick to anybody caught in the cone. If the target moves, the cone will follow it.
Parasite: Afflicts a random member of the raid with a 1,000 nature damage DoT. The Parasite will periodically leave the target and crawl to a new host, and may be killed during this time.
Type 3:
Frenzy: The Colossus will periodically enrage and do increased damage. Frenzy is dispellable only by a Hunter’s tranquilizing shot.
Death Abilities: The Colossus may also possess one of the following abilities which will be triggered upon its death:
Toxic Pool: A bright green pool of sludge will appear around the corpse of the Colossus, damaging any players in the vicinity for 2,000 every second.
Summon Colossus Lurkers: Two Colossus Lurkers will appear around the corpse of the Bog Lord. They have 140,000 HP each, no special abilities, and deal moderate melee damage on plate.
Summon Colossus Ragers: About a dozen Colossus Ragers will appear around the corpse of the Bog Lord. They have 35,000 HP apiece, no special abilities, and deal light melee damage on plate.
Refreshing Mist: Mushrooms will sprout from the ground, emitting a regenerative mist that heals nearby members of the raid.
Assignment Macros
/rw – INCOMING TRASH ASSIGNMENTS –
/raid SKULL – Tank #1 (Underbog Colossus)
Encounter Notes
Raid Leader Once the Colossus has used its first special ability, announce the type of Colossus you are dealing with in voice chat.
Type 1 Colossus
Melee DPS Run 30 yards away from the Colossus immediately when it uses the Spore Quake ability. You may return to DPS’ing when Spore Quake ends.
Paladin, 
Shaman, 
Druid Time allowing, you should cleanse any poison that afflicts the raid.
Type 2 Colossus
Raid If you are targeted by Acid Geyser, quickly run away from the raid to the left or the right. The Colossus will damage anybody who is standing between the two of you until Acid Geyser ends.
Type 3 Colossus
Hunter If you have the Tranquilizing Shot ability, use it on the Colossus whenever it enrages. Tranquilizing Shot is not required to defeat this mob, but it reduces his damage output.
When the Colossus Dies
Raid If a Toxic Pool appears on the ground, you must move out of it immediately to survive.
Tanks If either Colossus Lurkers or Colossus Ragers spawn, you must acquire aggro on them.
DPS If Colossus Lurkers spawn, kill them one at a time once the tanks have established aggro. If Colossus Ragers spawn, wait for the tanks to establish aggro, and then AOE them.
Questions about Hydross' trash? Discuss them on our Raiding Strategies forum.