This is a very Paladin-tank specific view, and you'll excuse me for that, I hope.
2 Tanks, 3 Healers (3 tanks)
This is it, the grand finale of Cataclysm. Nefarian took us the longest time to figure out and kill, about 4 full raid-nights all told. It is an incredibly demanding, technical and challenging fight and you don't really have a chance to have down-time at any point but the transitions.
Let's take it from the top.
Phase 1: Onyxia
You will need a dedicated tank and a dedicated healer on the Onyxia tank. That person should jump down first into the arena (hop onto the platform to minimize damage, and then drop to the ground and if you have a DK have them Glyph into Path of Frost for reduced fall damage.) Immediately build threat - Avenger's Shield and Judgment should both land right after each other and you can back up towards the wall to the right swinging at her the whole way. The rest of the raid will drop down right away and gather up behind her butt in her tail.
You will never need to move her, but it will make things a bit complicated for healers - watch your own health, her breath and tail lash - if breath and tail lash are coming together, hit a cool-down or ask for one. Use WoG exclusively and keep yourself topped off. With your healer stunned you will kill yourself on breath and melee if you're low. This is crucial - you really need to be on top of this. Keep her positioned like this and it gives everyone else room to position without getting to her sides and you mitigate the Lightning AoE part of the encounter entirely but you will have to deal with tail-whips instead.
As the fight starts, Nefarian will raise a few adds - this is where having a third tank makes life incredibly easy but if you don't have a third tank, or don't want one, you can use plate DPS or Kiters to pick up the adds. It really depends on your composition and skill-level. Keeping a DPS in Blood Presence alive through all the adds beating on them was unreliably tough. We were having luck with a mage and elemental shaman, but there were crunch moments where an add took a second or two longer to die and wandered over to a healer and so forth that for us, having a third tank gather them all in a clump and AoE tank them safely out of the way of everyone else against a wall eliminated a lot issues for healers. We used our DPS DK to do this.
As he comes in, the second tank picks him up and drags him all the way over to the other side of the platform. As soon as threat is established all the DPS swaps from Onyxia to Nefarian. By this point, we have typically shaved roughly 2.5 million health off of Onyxia. As soon as the last of the adds dies and the 3rd tank (now essentially in DPS mode) swaps to Nefarian, we hit hero and push Nefarian to 79% taking two Electricutes rapidly. Make sure the raid is topped off for this each time.
It is super important to coordinate tail-whips, Electricutes and Onyxia's Crackles and breaths. The Onyxia tank in particular will be taking massive damage and I use a major Shield Wall style cool-down for the first Electricute and two soft cool-downs at once for the second.
After the second Electricute everyone swaps back to Onyxia - she should typically be down to 2 million health or so just from tank damage, and you should have enough time to push her over before her energy meter hits 100 (we usually get her down with the meter ~90 with with a third tank.)
Phase 1 Transition:
Everyone should swap over to Nefarian and quickly DPS or DoT him up while running over to their (pre-assigned) platform, and then swim up to the adds to interrupt and heal. Using some kind of resistance boost for the fire damage helps tremendously here. I usually bubble myself.
Do not take an Electricute here unless your healers are able to heal up a million or so health on people as they scramble and separate. Just, don't do it.
Keep the adds interrupted and beat them down. The first AoE will happen even as you're scrambling on top of the pillars - the adds have massive hit-boxes so you can interrupt them from the lava if you absolutely have to. Do what you need to do as even a single cast of AoE plus the Shadowflame Barrage will wipe you.
Have ranged swap to the boss as their add goes down, or once two adds are down, however it works out better for you. Nefarian should easily be close to 73% health or so from phase 1 and any lingering DoTs and you can take another Electricute here - just make sure each paltform has some kind of raid damage reduction ability. Keep DPSing him while the third add dies and then get ready for phase 3. Unless you are very confident your healers can handle it, do not attempt a second Electrocute in the second phase. It helps a great deal in phase 3 but it can also wipe you very easily or at the very least cause deaths that will loose you any time you bought.
As soon as you jump, the Nefarian tank needs to pull Nefarian to the opposite side of the arena from where the adds are piled up. We deactivate all adds in the northern end of the platform and drag Nef to the Southern end, holding him with his flank pressed into the wall and the raid along his side in a clump. The raid has two jobs:
- Stay alive
- Kill Nefarian
That's it. If you don't need hero in phase 1, you should use it here, and early, to shave as much health off of Nefarian as possible. Keep the Electricutes in mind and do not hit those thresholds before your healers are ready. This is a burn phase, but with a bit of finesse required. Watch your health and use personal damage reduction abilities or immunities to ensure your survival. Watch your footing if fire creeps up to you. A dead character does 0 DPS.
The Nefarian tank also has two jobs:
- Stay alive
- Do not let Nefarian breathe on adds
The Burning Hell Of Kiting Skeletons:
This is the most difficult thing I have ever done in the game. You will need a dedicated healer, preferably someone who's okay with healing on the move. We have our restoration druid with me on this.
You will also need BigWigs or some other add-on that gives you very, very explicit and detailed timing on when Shadowflame is incoming - a general "5 seconds till Shadowflame lol" warning isn't sufficient and BigWigs does a good job of giving you an audio counter (go into settings and check it for explicit warning)!
The goal here is to kite the adds away from the spreading lines of existing Shadowflame and removing the adds from the location of the next shadowflame patch without spreading the fire so quickly that it takes over the arena and kills the raid. That's it. Sounds simple, right?
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The Adds have an energy meter that will slowly trickle down, and as it goes down to zero, they will reset, collapse, give you a brief breathing reprieve, and their stacking damage buffs will also drop. When Shadowflame (inevitably) gets to them, they will come alive again, with full energy but no stacks of damage buffs so they will have to rebuild from scratch giving you a chance to kite for a longer period of time.
Any exposure to flame - whether the fire coming from Nefarian, or the fire on the ground, or Nefarian's Shadowflame breath - will reset their energy to 100 and then you will have to deal with adds doing massive amounts of unhealable damage. As the fight goes on, Shadowflames come faster and faster, eventually capping out at once per 10 seconds making the kiting more and more hectic and fire starts to take over the room.
So. Let's take it from the top.
The reason you had them all in a clump was so that the first shadowflame will activate them all at once and give them all an even level of energy so they all reset at once. Move them out of fire a good ways, watch the pace that it's creeping up to you and make sure you keep them out of it, and wait for the next Shadowflame to be cast.
You want to move the adds between 1 and 1.5 seconds before the fire is cast just so all the adds start moving - if you wait for it to be cast before moving it is likely that one of the adds may tarry due to server lag, network lag or something else and you might wind up with one of the adds being clipped by fire giving you an uneven stack which is almost worse than having all your adds get hit.
There will be a purple mark on the ground where the fire will land but realize it will splash in a larger puddle than the marker - move the adds off completely and hold. Wait for the fire to begin moving towards you, position yourself so you know where to move and then strafe rapidly to get the adds away from the next cast. You should move enough so that the creeping fire isn't a threat but not so far that you spread the fire too much.
I try to keep the adds moving in tight arcs to give myself the space I can manage without taking any risks with clipping. Do not try to move backwards, you'll be moving too slow. You need to strafe or run straight back (not recommended unless it's an emergency and you hope you don't get crit from behind.)
You will need at least 2 resets before you raid is able to get Nefarian down to zero. The first reset is typically easy to manage as the Shadowflame comes fairly spread apart, but by the time they awake from that, you will be at the ten-second flames mark and you will be moving just about constantly. Coordinate with the Nefarian tank if you wind up on the side of the room that he's breathing on, and make sure you do not get a whiff of it on the adds. I've had adds with 10 energy get the faintest breath and all wind up at 90 and then kill me shortly thereafter. Utterly frustrating.
Once you can manage a second reset, you can typically just hold the adds out of fire without concern for their meters until Nefarian keels over as his health will be around 20% or so and you can manage to tank the adds through that amount of damage especially with a major cool-down.
This was tough and it took me a while to get it figured out.
I wound up regemming and reforge all my gear into mastery just for add-tanking phase 3. Paladin tanks should try to get to block-cap or as close to it as they can get. The amount of incoming damage you shave off is massive as all the damage the adds are doing is physical. I was close to 100% but still about 3% away from total block-cap.
Remember your healers will need to coordinate this with regular bursts of raid-wide damage from Electricutes. Try very hard not to use two of your cool-downs for anything other than for Electricutes. It took me a lot of discipline to get that part down - Glyphed Divine Protection for the first Electricute, Mirror of Broken Images for the next, and then you just rotate those back and forth. That's it.
Call for cool-downs from your healers if you absolutely need it - our priest tried to stay within range of me near the end so that she could hit wings on me if things got bad. You will need magic resistance on top of the physical damage during Electricutes and without it, you're dead. It's that simple. Exercise that restraint, and knowing that DP and Mirror are *only* useful against magical damage will help you from hitting them when the adds are doing a lot of damage.
Save Ardent Defender for the oh-shit-I'm-going-to-die and-Nef-is-down-to-2-million-health moment (it will come, trust me) and Guardian of Ancient Kings for when you miss that second reset and you're trying to stay alive so the raid can push Nef over before you drop (it will happen, trust me).
On our kill, we had Nefarian just below 20% right as we got the second reset and after the last Electricute, I just held the adds off to one side and didn't move except to shuffle out of fire while tossing Hammers of Wrath at Nef for some additional damage till he keeled over.
This might or might not work for you depending on your composition and DPS - it worked brilliantly for us, but it took us about four days to get to this point. Having a third tank in phase 3 was great to collect adds in one neat clump and was also insurance of a sort because if I missed a reset and Nef was really low, I could have the 3rd tank jump back into Blood presence and taunt two adds from me and hold them a little while longer while the raid works on Nef.
You might not need a third tank, which will help your phase 3 and with 5 DPS in phase 1 you might even be able to save hero for phase 3 and make it go that much faster - this is ideally how I would like to do it but for now, this is what works for us.
That's it. If you're add-tanking phase 3 - you have my respect. If you have a chance, do it now before this fight is nerfed to death. It's incredibly rewarding. :-)