Vexallus Vexallus is the second boss in the Magisters ' Terrace instance . He is an arcane elemental . Attacks and abilities . In heroic mode , Vexallus is immune to any taunt abilities . Strategy . Vexallus will spawn Pure Energy adds every time his health drops 15 % and starts to AoE the entire party at around 20 % health . These adds must be taken down immediately , otherwise they will start AoEing the entire party for ~ 2k each . When the adds are killed , the player who killed the add gains " Energy Feedback " , a debuff that causes 300 Arcane damage per second , but also increases all damage dealt by 50 % ( this debuff can stack multiple times , renewing its timer on application , increasing both the damage taken and the damage increase buff ) . Allowing too many stacks of the debuff to build up on a single player will likely kill them if the healer can not keep up , so it is best to spread them out among the tank and DPS ' ers , or otherwise . ( See : Sample Group ) . The fight is essentially a race against your healer ' s mana pool and maximum HPS ( healing per second ) . As more and more debuffs pile up , it becomes harder and harder to keep everyone alive ( similar to the combined Garottes in the Moroes fight ) . However , in order to kill Vexallus fast enough when he enrages , you must accumulate debuffs in order to increase your group ' s DPS ( unless you substantially out - gear the encounter ) . All damage dealt by Vexallus and the adds is Arcane ( including his melee attack ) and cannot be shield blocked or spell reflected . Stacking Arcane resist will help immensely , although high DPS must be maintained , and quick bursts of 5K - 6K damage are very common . The damage portion of the debuff from killing an add is not resistible in part or whole . Arcane Protection Potions will significantly ease the load on your healers . There are several ways to approach this fight , depending on group makeup . Heroic Strategy . Warlock Minion Zerging . Any group with a warlock speced for master summoner can make this fight so easy it ' s laughable . Simply have them summon a voidwalker , and have the voidwalker take the first set of sparks . From here you have two options depending on the group ' s dps . For a group with lower dps , simply sacrifice the voidwalker once it has taken the sparks and begin summoning a new one ; as long as you act quickly , you should have a voidwalker ready to take every single set of sparks . With a high dps group it is possible ( and safer ) to use health funnel to keep the voidwalker alive to take a second round of sparks . This lowers the risk of not having the voidwalker available to take the sparks , because your group will be spawning them rather rapidly . If your group is still getting overwhelmed with sparks it is recommended that your group slows down on dps until there is a voidwalker ready to take the sparks . IMPORTANT NOTE - Always sacrifice the voidwalker before the next one is summoned , otherwise you run the risk of resummoning it with the debuffs still applied . Druid Overload Strategy . Bringing any type of druid makes this fight much easier . Once Vexallus gets to ~ 20 % , have the druid use barkskin and tranquility . The amount healed will mitigate most of the damage which occurs when he starts his overload . Any druid spec can do this since tranquility heals for an enormous amount . It is critical to remember to barkskin , otherwise tranquility will end prematurely because of the pushback from overload . Off - Healer Strategy . For groups with a DPS that can act as a second healer , this fight gets much easier . The key is to take it slowly , spread the debuff from the adds around , and keep the in coming damage low . Make sure the adds die before they ' pop ' and lets some of the debuffs run out . Everyone can get healed up before each 15 % . Let the DPS takes the last couple adds so that they have a decent + damage going into the enrage . Have the healer switch to damage at 20 % and it should be simple . Strategy 1 . Two Pure Energy adds appear at 15 % health intervals until 25 % health remains , for a total of ten . Vexallus goes into Overload at 10 % , making any remaining adds more dangerous ; therefore , controlling your DPS may be necessary . Sample Group . A sample fight for a Warrior , Priest , Mage , Warlock , and Rogue group : As you can see , the key to this fight is to hit the " adds " as soon as possible . Providing this is done , the damage done to the DPS should be negligible . Alternate Strategy via Narkotyxx : If you have a shadow priest with a good arcane resist set ( 200 or above ) , he / she will act as the tank . Vexallus does arcane and nature damage only , so this will counter the lack of armor . Have your regular tank work on killing the sparks . I can vouch for this being I have done this a couple time already , with the encounter being easy . Just ensure that you hold the dps after each spark to let the debuff go off . Alternate Mage Strategy . A mage with the following macro can easily dispatch all of the Pure Energies in heroic mode , often collecting 6 - 8 debuffs at a time before wiping them with Ice Block , provided your group has enough DPS to finish him off during the overload without the + damage buffs . Warlock tips . A warlock can also tank this fight fairly easily , provided it has sufficient arcane resistance . With the following macro , the fight becomes simple ; This will ensure you hold aggro , while at the same time telling your pet to attack pure energy immediately , assuming you spam - click this macro . Using sacrifice on voidwalker when its about to die also helps a lot . Since there is no guaranteed amount of adds the voidwalker can take , considering the sometimes spontaneous movement of them , it is useful to have a macro to inform your group when your voidwalker is down , and let them know that its time for the next adds - taker . You can normally expect it to take two waves , using this strategy . It is not recommended to tank the boss if your arcane resistance is only above 200 due to your felhunter , as it will quickly drop when your felhunter takes adds . Either that , or the warlock ' s function as an adds - taker is wasted . Alternate Shadow Priest Strategy . Shadow Priests offer a cool way to handle the fight using Vampiric Embrace . Simply have the priest kill 3 - 4 of the adds to increase damage by 150 to 200 % . Apply Vampiric Embrace , dot up Vex and the passive heals will heal the shadow priest through the periodic damage of the debuff . Its helps to have a tank with good threat generation or perhaps have the tank kills one or two of the adds to increase their threat generation . Patch 3 . 0 . 2 . As of patch 3 . 0 . 2 , the damage from the Energy Feedback is now resistable . Assuming that this is not reverted , this fight has become laughably easy . Any tank , assuming a heroic - level life pool ( ~ 12000 ) , that stacks arcane resistance gear past 300 should be able to tank this in heroic without issue . Quotes . Aggro : Discharges Energy : Overload : Kills you :