You can find an SL warlock outside IF or Orgrimmar, this is the place were most SL warlocks hang out.
To initiate combat, you should approach the warlock and talk to him. He will say something about how nerfed warlock 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:
The warlock will begin the fight without a pet, because he will feel too overpowered to use a pet against you. MT#1 and MT#2 should position the warlock 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, and one of them should also have 250 fire resist minimum. (This is explained later). 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 warlock, 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 warlock will perform a series of attacks:
SHADOW BOLT: A bolt of shadow is launched every 4 seconds to the tank that has aggro, causing 1200 to 2500 shadow damage, depending on resistance. A shadow bolt will crit between 3500 and 6500 damage, again depending on the target resistance. This is were MT#2 should come into play: If a Shadowbolt crits MT#1, he will have a debuff that will increase Shadow damage by a Zillion times. This is when MT#2 should taunt the warlock to prevent MT#1 from dying. MT#1 will then do the same thing once another Shadowbolts crits MT#2.
Curse of Doom: Every 1 minute, the warlock will cast CoD on a random raid member. This member should move outside the raid and unload full DPS, since he will die within the minute.
Shadowburn: The warlock will cast Shadowburn everytime he changes target. If one of the raid members gets aggro, he will suffer shadowburn and instantly die. It is important not to OverDPS, or members will die one after another.
Fear: The warlock will cast Fear on a randomy raid member, every few seconds. You should provide everyone with Fear Ward if you have it, and dispel fear ASAP, especcially on MTs and Healers.
Phase 1 is relatively easy and will last until the warlock has 70% life. This can take between 3 and 5 minutes, depending on your equipment.
When the warlock reaches 70% life, he will instacast a felhunter and Soul Link it. This is when the fight becomes harder.
Note: You cannot kill the warlock while the felhunter is alive. If you try to, the warlock will say that It's not his time yet and will use an healthstone, which will probably render the fight impossible in phase three.
A few moments before Phase two, the raid should move as shown in the pic.
Note: MT#3 and MT#4, which are tanking the felhunter, should stay at least 10 yards away from the warlock
Phase two is all about killing the felhunter.
The felhunter CANNOT BE DAMAGED by magic, as it has very high magic resistance. Also, during phase two, you should not magic debuff the pet or the warlock, otherwise the felhunter will remove the debuff and heal himself.
MT#1 & #2 should stay on the warlock with a few healers, while the melee DPS group will take down the Felhunter, while the magic
DPS group focuses on the warlock. During this phase, the warlock will receive next to no damage, as he is Soul Linked to the pet.
During Phase two, the warlock will have a new attack at his disposal:
Hellfire: Every 20 seconds, the warlock will cast Hellfire and hit anyone within 10 yards for an incredible amount of Fire damage.
Every DPS class standing near the warlock should retreat as shown in the picture and bandage as soon as he casts hellfire. Only the MT with Fire resistance should remain near the warlock. This is done because if the warlock finds no one within melee range during Hellfire, he will summon an Infernal and wipe the raid.
When the Felhunter is dead, PHASE THREE begins.
Phase three will begin as soon as the Felhunter is dead.
Notes: The warlock 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 warlock will use all his arsenal to kill you.
Curse of Shadow/Elements/Agony: Every 10 seconds, the warlock will cast a random Curse on the entire raid. These debuffs should be removed as soon as possible. If CoE or CoS are not removed after 10 seconds, the warlock will cast Immolate/Shadowbolt on the member, killing him.
Howl of Terror: The Warlock will randomy cast HoT, hitting all the melees around him. You need to be quick and dispel Fear on the MTs otherwise they will lose aggro.
Death coil: The most imbalanced spell in the warlock's arsenal. This spell will be cast on a random raid member killing him, and will heal the warlock. CT_raidassist will warn you when the warlock is about to cast Deathcoil, and all Healers should hide behind the tank. If more than 3-4 healers are killed, the MTs will not be able to sustain damage and die, wiping the raid.
Note: In this pic ( http://img336.imageshack.us/my.php?imag
When the warlock is at 5% life, he does an emote saying "Imba Warlock performs one last service for Blizzard" He will then cast Curse of Doom on the entire raid. This means you need to kill him within one minute, or you will wipe. You should have at least 15-20 DPS classes still alive here, otherwise you won't be able to kill him in time.
If you manage to kill him within the minute, congratulations! You just killed the hardest boss currently in World of Warcraft!