When discussing how the changes coming in Warlords of Draenor will affect raiding, we're of course looking at an incomplete picture. We don't know what new spells and abilities might come, we just know to an extent what won't be there - abilities like Skull Banner will be gone, as well many CC abilities, and healing will be greatly changed - casting on the move will also see a significant decrease. What we therefore need to consider is that raiding itself will have to change to embody these changing philosophies. It would be a disaster to alter class abilities and leave raids designed around the same high damage, high mobility kit we see in modern raiding.
But what will raid design entail? Well, I'm not a raid designer. If I was, I'd be super busy designing some raids. What I am is a guy who raids a lot, so I can give you my perspective as a dude who has seen every fight in the game at this point. What are we in for in Warlords, based on what Blizzard has said is changing, and what they intend to try and do?
- There will absolutely still be things you should not stand in. Raiding has leaned heavily on the 'this is bad, don't stand in it' pillar since day one. This is not going to change. Most things you're not supposed to stand in now don't instantly kill you, but they'll kill you in a few ticks if you don't move - expect that to continue.
- There will be less interrupts and CC expected overall. I am not saying there won't be interrupts needed from your raiders. I'm saying that with interrupts lacking silences and less overall interrupts, you'll end up with fewer required. This will also be the case for CC - if there are adds that require CC, there will be fewer of them.
- There will be less `You die now`abilities. Bosses will still do damaging spells and abilities (especially on tanks) but there will be fewer abilities that can just kill you outright unless they can be avoided in some way - massive damage that has to be healed through won't be as common in the triage model.
- Movement fights will be more clearly demarcated. Right now, some fights are all movement, all the time. I do not expect that movement will be gone from fights, but I do expect that there will be less awful movement. Fights like Durumu are not likely to be seen again. But raiding isn't going to turn into a series of Patchwerk fights - you will have to move.
- Mythic Raiding may break all of these. The difficulty line between mythic raiding and what will be called heroic raiding (which is basically the same as what we call normal mode now) will be much sharper than the current normal/heroic divide. Because of their 20 player size, they will likely be designed with the expectation of min-maxing, bringing specific classes for buffs, raid cooldowns (they'll be designed expecting Bloodlust, for instance, and probably will assume at least 1 of every class) and I don't expect it to be nearly as easy to jump into mythic as it has been to stick your toe into heroics.
This may accidentally serve to make raids more melee friendly by the simple fact that it will reduce the current massive advantage ranged DPS bring to the table. If stacking ranged will actually provide a disadvantage on certain fights, raids will be forced organically to start balancing out their ranged and melee to a degree, instead of the current situation where bringing 5 melee to a 25 man raid is seen as a lot of melee.
We'll also see less DPS from tanks with Vengeance no longer providing offensive benefit and tanks designed around doing about 75% of an equally geared DPS player, making the DPS contribution of individual DPS players the more valuable. This means that tanks will be less likely to be selected on the basis of their DPS, putting the emphasis back on survival (where it belongs). Vengeance will still provide defensive benefit (on warrior Shield Barrier, for instance) so tanks will still get an advantage as fights wind onward. DPS thresholds will have to be adjusted for the loss ranged will see during movement fights, of course.
Overall it's an interesting paradigm shift. We'll see how it plays out - I expect we'll see fewer mythic raids than we currently see heroic, due to the loss of 10 and 25 man heroic raid guilds and the fact that semi-casual 10 man guilds won't be able to dip their toes into heroic raids the way they do now. I also expect that as we get used to mythic as a raid size, we'll start to see guilds recruiting for that benchmark and keeping a roster around 20 to 30 players (especially if normal/heroic ends up flexing as high as 30) that they bring on their flexible raid sizes to keep them geared up. This may end up making some guilds much more focused on their benches than they are now.