Hydross the Unstable / Resistance Gear Hydross the Unstable is the first boss of Serpentshrine Cavern in Coilfang Reservoir . He attacks solely with Frost - based damage in his Pure Form , and Nature - based damage in his Corrupted Form . Hydross also spawns 4 adds when he switches between each type ; their damage matches the Form he changes to . In order to survive his magic - based attacks , the tanks require sufficient levels of resists . The usual approach is to have one tank maxed on Frost Resist and one tank maxed on Nature resist ; these two tanks will manage Hydross . There are also additional tanks with a mix of Frost and Nature resist to pick up the adds that Hydross spawns on each transitions . Resistance Basics . 365 is the resistance cap against a lvl 73 mob . At 365 , it is considered to be at a ~ 70 % average damage reduction ( they will be resisting 75 % of the damage 80 % of the time - see Resistance for more information , but be aware that elemental melee damage does not behave exactly like spell damage ) . Hydross hits for ~ 8 , 000 unresisted , so this should make the average damage about 2400 . The way resistance works , the amount of damage actually resisted will fluctuate from 75 % resists to 25 % resist ; so healers remember that this is an average , and your tank will still take spikes . Here are some suggestions on your resist sets . You only need 365 resist against a level 73 mob anything more is WASTED . So you should only need the core plate set and a couple other items . Frost resistance . Since the maximum effective resistance caps at 365 ( anything over has no effect ) , you do not need every item listed , and can vary it slightly . Once you have all the items and you are down to enchants , if you choose only one enchant with + 7 , you will only obtain 364 resistance . If you go for the shield enchant , you can hit exactly 365 ( including aura / totem ) , or you can go for two enchants and have effective 365 . While it is untrue that being at 364 resistance puts you down to the 50 % threshold , you should strive for 365 , because going from 364 to 365 yields the greatest return on your time - to - live compared to going from 0 to 1 . Note : This wasn ' t taking into account GotW from druids which most all raids will have available and conveys 33 resistance . With that taken into account you can forgo some of the expensive enchants . A Shaman ' s Frost Resistance Totem can be used in place of the Paladin ' s Aura . Nature resistance . One could always substitute a Savage Guard from Zul ' Gurub for the legs augmentation , which will push the nature resist to 365 ( 366 actual , but effective is 365 ) . A Shaman ' s Nature Resistance Totem can be used in place of the Hunter ' s Aspect . Druid Off Tank Gear . Despite the following table , most of a druid ' s non - crafted resistance gear will likely be BoE random enchantment gear from the AH - either of Frost Protection , or of Nature Protection . The rest should have resilience / defense rating , stamina , and agility . Resilience gear works very well for this fight , and the entire amount can be handled by , , , and , leaving almost all slots and enchantments open for resistance . Other buffs . Besides the group - based resist auras , there are additional options to raise your resistance . These are especially useful if your gear isn ' t complete yet or to be able to allow more gear options ( increasing stamina , for example ) .