Grimoires and Hellfire

Early in my experiences with WoW, I did not particularly like Warlocks. This may come as a shock to those who started playing more recently than I do, but Warlocks were, during much of Burning Crusade, "that class." What I mean by "that class" is that it was the class that everyone was playing. At the time, Warlocks (Affliction, mainly) were real powerhouses in PvP. If I recall correctly (my Warlock, Morcanis, was only in the teens I believe by the time I decided to actually level him during Wrath of the Lich King,) a Warlock could put Curse of Agony (as it was then called,) Corruption, Unstable Affliction, and I think even Immolate (before they kept UA and Immolate from stacking) on you all at once and then fear you, causing you to run around the battleground as your insides melted/dissolved/burned, screaming and unable to do anything while the Warlock just laughed.

BC was a different time. Back then, many PvE'ers would run Battleground after Battleground (or Arena, though that was truly for the hardcore) to get the most easily-acquired epics. This was a time when success in a heroic dungeon run was hardly a given. Even with all the resilience on the gear, you could get stuff that was miles ahead of what you were getting in heroics or Karazhan (few raiders were able to progress beyond Kara, especially given the jump from 10-mans to 25-mans. The original Zul'Aman was created to give 10-man raiding guilds a place to move on to.)

Anyway, the point is that PvP power led to PvE power, and so Warlocks were immensely popular.

While I never had any doubt in my mind (at least, once I'd figured out how talent trees were supposed to work) what spec Jarsus or Tarbhad, or Darsino should be (I've grown fond of Assassination, but at heart I prefer the flavor of Subtlety,) Morcanis was always a character I struggled with. Eventually, with the advent of the Felguard and Metamorphosis, the decision was made, and in fact, the more they play around with Demonology, the more I find I like it.

Other than the Monk (who is, of course, in the process of invention,) Warlocks are getting the biggest overhaul with Mists of Pandaria. I can't speak to Affliction, as I have not tried it out, but my understanding is that for the most part, Aff locks are getting the fewest changes. Demonology and Destruction, on the other hand, are getting entirely new resource systems (akin to Runic and Holy Power, respectively, sort of - though really they're pretty unique, new systems.)

I'll start with Destruction, because it's the one I know less about and we can get it out of the way. First off, Banes are gone for both Destro and Demo. In fact, Immolate is now Destruction-only, and replaces Corruption. So that's one DoT. Soul Fire, also, has seen huge changes that affect both D-spec (I don't think Affliction uses it, though I could be mistaken.) Soul Fire now always crits. Addtionally, Destro locks will gain power of Burning Embers whenever they Incinerate a target with Immolate on it (which is what you'll be doing most of the time.) The Embers take a few Incinerates to build up, and max out at 3 (4 with a glyph, I believe,) but once you have one, you'll literally catch fire. Now, this is where I could be wrong (and I'm too lazy to look it up,) but I think the more Burning Embers you have, the more powerful your spells will be. However, the more Burning Embers you have, the more damage you'll take as a self-inflicted DoT.

The flavor is quite well-reflected in the spec's design. Destruction Warlocks are insane pyromaniacs, with a fervor for chaos that would make Twilight's Hammer go "whoa, whoa, careful there, buddy." Destruction also is interesting in that Life Tap is gone, but instead they regenerate mana at a much higher rate. Destruction is going to play fast and hard. Seems like the perfect spec for a Goblin.

Demonology goes in a different, but also very interesting new direction.

The first thing to note is the new secondary resource, Demonic Fury. Various abilities build up Demonic Fury, which increases your damage done and also powers your demon form.

Metamorphosis was always a cool ability, but other than the few, mainly flavorful abilities you get with it, it was always pretty much a glorified cooldown that scaled with Mastery. Metamorphosis is much more important now. First off, there's no more cooldown, and you will be expected to toggle in and out of Meta-mode to play effectively. Meta will do a couple things: you won't be able to cast basically anything except Demonic Slash - which Shadow Bolt automatically transforms into - and Soul Fire. However, your damage is increased and none of this costs mana - instead it costs Demonic Fury. Simply being in Demon Form will drain your Demonic Fury, so ultimately, you can't stay in it forever, but wait, because the next part is fantastic.

Wild Imps. Currently, Bane of Doom has a chance to summon a little Imp that attacks your targets with weak melee. It's not totally insignificant damage, but it's certainly not your most crucial component. Wild Imps will be summoned when you use Shadow Bolt, with a 15-second internal cooldown. Their fire bolts will then charge you with Demonic Fury. If you want them out quickly, there's also a separate spell (on a cooldown) that pops 5 out at once.

So what this means is that you'll truly have a small army of Imps, your main summoned demon, yourself in Demon Form nearly half the time, and on important fights, a big, scary Doomguard (or Terrorguard, with the talent.)

Hand of Gul'dan's been heavily redesigned, and is now ground-targeted (which is actually one thing I'm not crazy about) but it will help get your Demonic Fury flowing.

Anyway, Warlocks are getting some serious love this expansion. Assuming thing remain on this trajectory of awesome, I expect Morcanis will see a lot of play over in Panda-land.