Serpentshrine Cavern Hydross the Unstable The Lurker Below Leotheras the Blind Fathom-Lord Karathress Morogrim Tidewalker Lady Vashj Hydross the Unstable is the first boss of Serpentshrine Cavern. Entrance Hydross the Unstable Abilities Hydross has two forms, depending on whether he is in the water beams or not. Thus the players control which form they deal with. Water form : He casts this when he enters the water beams, making it a player-determined occurrence. It will make him enter a purified state in which he is immune to frost and will hit for frost damage. When casting this, he will also spawn four Pure Spawn of Hydross. These are also immune to frost and also hit for frost damage. : Stacks up to 5 times, increasing frost damage received by 10, 25, 50, 100 and 250 percent. : Casts on a single target every 7 seconds. Stuns for 4 seconds and deals 4500 frost damage over 5 seconds (which means that anyone getting this with a 100% debuff needs to be healed before the DoT ends). It also applies to all people within 8 yards of the original target, but it won't chain to secondary targets. Poison form Once he leaves the water beams, making it a player-determined occurrence, he will no longer be in a purified form. He will become immune to nature and will hit for nature damage. When this happens, he will also spawn four Tainted Spawn of Hydross. These are also immune to nature and also hit for nature damage. : Stacks up to 5 times, increasing nature damage received by 10, 25, 50, 100 and 250 percent. : Casts every 15 seconds. Deals 500 damage each 3 seconds and reduces healing and damage done by 50%. Lasts 24 seconds. Hydross will enrage if not killed within 10 minutes, wiping your raid in a matter of seconds. Strategy Have your Main Tank pull Hydross by going to the right (against the pillar) and charge/intercept him. His aggro range is quite big so be careful or he will change to poison form at the beginning of the fight and you will lose a lot of time killing the first four adds. Once your MT is in place at the center of the platform, try to spread your raid. Don't hesitate to go behind Hydross, you won't have many line of sight problems in this fight. You now have one minute to DPS him, this is a very important part of the fight because it's the only moment where you can DPS him without having to handle adds. After about 1 minute, you will reach the 100% damage increase from the Mark of Hydross, this is the time to move him to the edge of the platform to change him into his poison form. Make sure he doesn't have too many DoT's on him at this moment, Hydross resets his aggro but not his debuffs, which means that a warlock who has put too many dots on him will get aggro and die. When Hydross changes to his poison form, he will spawn 4 Tainted Spawn of Hydross, which you can crowd control. Kill these adds as fast as possible, you only have one minute before you've got to change Hydross' vulnerability again which gives you only not more than a few seconds to DPS him once all the adds are dead. Make sure you don't banish too many of them or you will have to wait before you can kill them. After one more minute, it will be time to switch him back to Pure form, by letting the MT run to the center of the platform. Don't forget to stop DoTs again. Now 4 Pure Spawn of Hydross will spawn, these are water elementals, which means you can't use frost trap/frost nova to CC them, but banish still works. Off tanks with some frost resist gear are really useful here if you don't have enough warlocks. Repeat until he's dead. General Tips It is advisable to use two MTs, one with high nature resistance and one with high frost resistance. Druid off tanks with a mixture of frost and nature resistance gear and high stamina can help with the adds. Spread out as much as possible to avoid the Water Tomb. When Hydross is around 15%, it is recommended to use all forms of CC on the spawns and do as much damage as possible on Hydross. Best moment to use those high damage, long cooldown moves.