Recently i saw an enormous amount of posts regarding shadowpriests, dispersion, and how overpowered and imbalanced shadowpriests are.
To help you fellow players, i've decided to write a guide, being a shadowpriest myself, so that more people can succefully defeat shadowpriests on their battlegroup. This will be a comprehensive guide containing images, spoilers, tactics, and tips to defeat this imba class.
You can find an shadowpriest outside IF or Orgrimmar, this is the place were most shadowpriest hang out.
To initiate combat, you should approach the shadowpriest and talk to him. He will say something about how nerfed shadowpriest were, and how they could not kill anyone in previous patches, and how they became godlike while mages are now water dispensers. After you talk to him, click DUEL to start the fight.
You should position yourself as shown in this image: Phase 1
The shadowpriest will begin the fight without a shadowfiend, because he will feel too overpowered to use a shadowfiend against you. MT#1 and MT#2 should position the shadowpriest so that his back will face the tank farther away from the IF door. It is advisable for them to have at least 350 shadow resistance. Greater Shadow Protection pots are also a good commodity, as Whipper root tubers and +50 stamina potions from the quest in Blasted Lands.
The melee DPS group (shown as YELLOW in the pic) should stay behind the shadowpriest, near the tank farther away from the Gate. This is done because they will need to retreat behind the tank and bandage, from time to time. (Bandage spot is shown on the pic)
The rest of the raid should position as shown in the picture. It is important for the raid to have about 120-200 shadow resistance, which will help sustain the damage. Keep in mind you will need at least 2 dispellers for each debuff type, otherwise you will wipe pretty soon.
During Phase 1, the shadowpriest will perform a series of attacks:
Mind Flay: A flay of shadow is launched every 2 seconds to the tank that has aggro, causing 5000 to 8000 shadow damage, depending on resistance. Mindflay will crit between 8000 and 10000 damage, again depending on the target resistance. This is where MT#2 should come into play: If a Mind Flay crits MT#1, the shadowpriest will have a buff that will increase Shadow damage by a Zillion times. This is when MT#2 should taunt the shadowpriest to prevent MT#1 from dying. MT#1 will then do the same thing once another Shadowbolts crits MT#2.
Shadow Word: Death Every now and then the shadowpriest will cast SW, killing a random raid member.
Mind Blast: If a target is affected by Vampric Touch, the shadowpriest will use Mind Blast to instantkill the person, and restore his mana to full.
Devouring Plague: The shadowpriest will cast Devouring Plague everytime he changes target. If one of the raid members gets aggro, he will suffer from the plague and instantly die. It is important not to OverDPS, or members will die one after another.
Phase 1 is relatively easy and will last until the shadowpriest has 70% life. This can take between 3 and 5 minutes, depending on your equipment.
When the shadowpriest reaches 70% life, he will instacast a shadowfiend. This is when the fight becomes harder.
Note: You cannot kill the shadowpriest while the shadowfiend is alive. If you try to, the shadowpriest will say that It's not his time yet and will use an healing ability, which will probably render the fight impossible in phase three.
Note: MT#3 and MT#4, which are tanking the shadowfiend, should stay at least 10 yards away from the shadowpriest.
Phase two is all about killing the shadowpriest.
The shadowfiend CANNOT BE DAMAGED by melee, as it has very high magic resistance. Also, during phase two, you should not magic debuff the pet or the priest, otherwise the shadowfiend will cast shadowcrawl and kill the tanks.
MT#1 & #2 should stay on the shadowpriest with a few healers, while the caster DPS group will take down the Felhunter, while the melee DPS group focuses on the shadowpriest. During this phase, the shadowpriest will receive next to no damage, as Inner Fire prevents any serious melee damage.
During Phase two, the shadowpriest will have a new attack at his disposal:
Mind Sear: Every 20 seconds, the shadowpriest will cast Mind Sear and hit anyone within 10 yards for an incredible amount of Shadow damage.
Every DPS class standing near the shadowpriest should retreat as shown in the picture and bandage as soon as he casts Mind Sear. Only the MT with Shadow resistance should remain near the shadowpriest. This is done because if the shadowpriest finds no one within melee range during Mind Sear, he will start using silence on the healers and wipe the raid.
When the shadowfiend is dead, PHASE THREE begins.
Phase three will begin as soon as the shadowfiend is dead.
Notes: The shadowpriest should be at around 40% health now. If he's any higher than that, you'll prolly not be able to take him down before you wipe. Also, if you have more than 6-7 dead members by now, you will probably wipe as you can't do enough DPS.
During phase three, the shadowpriest will use all his arsenal to kill you.
Shadow Word: Pain/Vampiric Touch: Every 10 seconds, the shadowpriest will cast a random debuff on the entire raid. These debuffs should be removed as soon as possible.
Phychic Scream: The shadowpriest will randomy cast Phychic Scream, hitting all the melees around him. You need to be quick and dispel Fear on the MTs otherwise they will lose aggro.
Silence: Every 45 seconds the shadowpriest will silence a caster, but if no casters are in range, a healer will be silenced, with the a tank death as the result.
Dispersion: The most imbalanced spell in the shadowpriest's arsenal. This spell will be cast if the shadowpriest gets low on mana, making him immune while dots kills off parts of the raid.
CT_raidassist will warn you when the shadowpriest is about to cast Dispersion, and attempts to interupt the instant spell should be made. If more than 3-4 healers are killed, the MTs will not be able to sustain damage and die, wiping the raid.
When the shadowpriest is at 5% life, he does an emote saying "Imba shadowpriest performs one last service for Blizzard" He will then start casting Shadow Word: Death on the entire raid.
This means you need to kill him before the entire raid is wiped out.
If you manage to kill him before that, congratulations! You just killed the hardest boss currently in World of Warcraft!
(Originally written as "How to beat a warlock" from the official forums anno 2006)