The emphasis of an Affliction Warlock is it's mobile, multi-target capabilities combined with an insane level of self regeneration. Essentially a battle begins from a stationary position, but once that first cast the Warlock is always moving unless you need to stop for a quick Drain Life or Drain Soul top-up of Health or Mana. You usually only stop once everything in range is dead. This is not a style to be played in the same abrupt fashion as an AoE mage, think of it as more of a dance with the devil and the deep blue sea. There is a fluid elegance to the Affliction Warlock.

Your offensive spells are grouped in a few loose categories, but will primarily focus on Damage over Time spells.

Opener:
Your typical opener is Unstable Affliction. This causes 1050 damage over 18 seconds. While casting, turn in the direction you are planning on running to which will preferably be towards your next victim. As soon as UA is cast, drop your Curse of choice and start running. If timed right, the Curse will be cast almost immediately after UA ends. It's weird. But it works. Or maybe it's just my lag.

Curses:
There is a wide variety of curses to choose from, and that choice is perhaps the most difficult part of playing a Warlock. If you expect a mob to be mobile for 24 seconds your best choice is likely to be Curse of Agony. It deals 1320 damage over 24 seconds, but it's damage is weighted towards the last 6 seconds. If the mob dies before hitting 18 seconds, it is better to use a different curse. Or even no curse at all. Other curses:

• Curse of Exhaustion: Reduce movement speed by 30%. Good for kiting
• Curse of Weakness: Reduce AP by 350 for 120 seconds. When tanking Unfearable Mobs with the Voidwalker, this helps keep it up and keeps your aggro down so you can manage the fight better.
• Curse of Recklessness: Increase AP by 180, reduce Armour by 800 and force mob to attack. This stops them running when under "Fear" and is useful to keep them from running into a pack of mobs. By alternating this with another Curse you can effectively Fear ping-pong a mob without risking adds.
• Curse of Tongues: Increase casting time by 50%. Against casters. Incredibly useful.
• Curse of Elements: Reduces Fire and Frost resistances and increases the damage taken from those. Useful when grouping with mages, but unless you are Destruction specced not useful to a solo warlock.
• Curse of Shadow: Reduce Shadow and Arcane resistancs and increase the damage taken from those. Useful when grouped with another Warlock, Shadow Priest or even an Arcane Mage. Solo it is useful as well for short burst fights where Curse of Agony will not run the full duration.
• Curse of Doom: 3200 shadow damage after 1 minute. This receives a massive boost from +Damage effects, 200% if I recall correctly. In Elite / Boss fights, this is invaluable as it is usually a finisher and a life saver. There is a chance it can spawn a Doomguard though. Of course, if you're mad like me - that is a desirable side effect.

Corruption:
Only one corruption spell can be cast, but you only have a choice of two so this is hardly a difficult one. Corruption itself deals 906 damage over 18 seconds. Through talent points it becomes an instant cast spell, so this is staple. 9/10 of your fights will have this cast. The other choice is Seed of Corruption, which is an interesting little spell. I have found it useful against lower level mobs where I can tank a large number of them without worrying about spell interruption too much. It has a casting time, so is mostly useful as an opener to give you time to finish the cast. This spell deals 1044 Shadow damage against the target. As soon as the target has taken 1044 damage, the Seed will inflict 1110 to 1290 Shadow damage against all enemies within 15 yards. As you can imagine, with a few seeds embedded you can mow down mobs at a rather alarming rate. The casting time is a snag though and you need to keep the mobs grouped, otherwise the Seed loses it's effectiveness.

Miscelleaneous DoTs
Immolate is another DoT, but it is fire based and has a casting time. This is more of a destruction spell. The other miscellaneous one though is Siphon Life and this is useful. Very useful. It transfers 63 health from the target to the Warlock every 3 seconds for 30 seconds. It does not sound like much, but stack on +600 damage which bumps this spell to ~+140 health and the +20% increase to healing effects from Fel Armour and throw it onto multiple mobs, you are healing approximately 600 health back every 3 seconds. For free, in essence.

That covers the DoTs. So, resuming where we were. A mob is currently roaring towards you with Unstable Affliction on it. You've cast Curse of Agony, Corruption and Siphon Life on it while running closer to it's friend. Target the friend and cast Curse of Agony, Corruption and Siphon Life while circling towards your third target. By now the first mob should be on approximately 30% health. Repeat with the third mob. At this stage you should be running low on mana. You can either Dark Pact to drain 1200 mana from your pet, or use Life Tap to regain 1200 mana from your health. Grab another mob or use Howl of Terror (Instant cast thanks to Talents) to Fear them off you. That buys you 8 to 12 seconds of peace, in which you can regather your mana, Life Tap as necessary and Drain Life the last mob to regain your health. If you switch to Drain Soul right at the end, you can gain 15% of your mana back along with a Soul Shard.

How do you supplement all of this? Easy. Keep Fel Armour up and running at all times. That gives you +100 damage and +20% on all healing effects, including potions and Healthstones. Always, always keep a Healthstone up and if possible, keep a Soulstone up and running as well. Use the timer on Fel Armour to tell you when to recreate and recast your Soulstone.

From time to time Nightfall will proc. This gives you an Instant Cast Shadowbolt. That is 541-602 damage begging to be released and makes a good finisher. Shadowburn is also a good finisher and will usually take any dotted mob on 30% down immediately. It consumes a Soulshard, but if the mob dies within 5 seconds of the attack you regain that shard. Both of those are invaluable in PvP.

Pets:
In terms of pets, the Affliction Warlock can literally go with any of them. The Imp is your usual choice because it costs no shards to summon, gives you a +66 stamina bonus and as it has the highest spirit and intellect will regain mana the fastest. It is a mana battery that is immune to threat, because you keep it phase shifted all the time.

The Succubus makes a good choice as well. She is slightly more melee oriented than the Imp and won't hold an Aggro candle when compared to her Warlock you, but her Seduction ability against humanoids is invaluable for surviving any ganking.

The Felhunter is a brilliant pet. Expect mana regeneration to be somewhere between the Succubus and the Imp, but it's abilities drain mana rather quickly. Of note is it's Paranoia buff, which greatly increases stealth detection. It can however silence enemy casters through Spell Lock and can use Dispel Magic to eat beneficial buffs off them or to devour harmful spells off you. A brilliant PvP companion.

The Voidwalker should not be ignored completely. As a tank, he is the best of the pets available to us, but once you've Sacrificed him for that glowing shield you begin to appreciate what it is like to be a Paladin that can DPS too.

The last pet that deserves a mention is the Infernal. It breaks free from your control after five minutes and will go on a stomping rampage, but you can re-enslave it. It is however an insanely overpowered animal. The sheer amount of hurt it can inflict is tremendous and it's entirely feasible to let it loose against some mobs and just watch as it obliterates group after group after group.

Right, that is an essential summary. I will edit at some future date to include some more tactical tips and tricks.