Thanks for clearing that up. I went back to give Hakkar another go, this time with Arlokk dead (had a priest tag along to take the mark and help me AOE and heal).

With Arlokk dead, Hakkar doesn't Mind Control anymore. Since the Aspect of Arlokk causes my pet to "vanish", then what happens is my pet gets removed from Hakkar's aggro table while my pet is stunned. Hakkar is then able to MC the player with the highest aggro on his list, which would be me. But with the aspect no longer a problem, my pet doesn't get removed from Hakkar's aggro list and I don't ever get MC'ed again. The fight now becomes a simple matter of keeping Mend Pet up and remember to bandage every once in a while.

The "vanish" would explain why, while I was MC'ed, sometimes Hakkar would reset to full health (and then proceed to re-aggro onto me once MC wears off). It's because nothing, not even my pet, is on it's aggro list. I thought the aggro wipe would just reduce my pet's aggro to zero instead of completely removing my pet from the fight.

[Essence of Gossamer] is a real boon in any soloing situation, since its proc will reduce damage taken (it unfortunately seems to have a rather long ICD) and its high stamina means you're getting more mileage out of Imp. Leader of the Pack.

It may be obvious, but managing cooldowns is an important part of pulling these fights off. Barkskin and Frenzied Regen should be used whenever possible, allowing that you should probably save Barkskin for big bursts (like Mag's fear). Demo roar should obviously always be up, and having peope offline in your party contributes a surprising amount of mitigation via Protector of the Pack (I believe I had two people offline in my group for 6% total mitigation when I was there).

Magmadar is something of a balancing act, and you need a little luck unless you want to clear the corehounds (and they're a real pain). I used 2t5 for the instant regrowth (socketed for intellect for ILotP mana boosts, though i may try resocketing for stamina) and tanking gear in the other slots. Without 2t5 you may have a significantly harder time, but he's probably still doable.

I saved Berserk for when it looked like I was going to get feared into corehounds (and was lucky enough not to be feared into them when it was down - keep him as far back against the wall as you can). Barkskin is most important when you're going to be in caster healing, obviously, but it can also reduce damage taken when feared significantly.

For Garr, the key is 1) killing all the adds before you die, and 2) being able to drag out the fight against Garr himself indefinitely. (the strategy for Lucifron is similar, except that you likely can't pull off forever against him until he runs out of mana, so the situation is a lot stickier early on). Go into the fight with a full HoT stack on, blow all your cooldowns getting him down (Berserk right away; the sooner the adds start to die the sooner the damage reaches consistent levels) and just throw everything at him. I used last stand, Fregen, a charged crystal focus, health potion, barkskin, ([Essence of Gossamer] proc is unbelievavle here) and so on, then kept myself up with 2T5 once the adds were dead. It didn't occur to me until later, but you might also try using entangling roots to keep an add out of the fight, then renewing with Nature's Grasp when that wore off.

The biggest thing for any of these fights is that you're going to need a way to heal consistently - more often than FRegen will allow, for sure. If you don't have access to 2t5 (and I really recommend you get it, for situations like this it's just invaluable) then that most likely means shifting and healing, likely without Barkskin at least some of the time. Casting in caster is likely a losing proposition overall - the best way is probably to set up a macro to switch healing weapons on while in bear, then Regrowth > Rejuv > back to bear. You may just end up taking too much damage, though.

To mitigate the amount of times you have to heal (since you won't gain very much health and it's precarious at best, especially on Mag where getting feared in caster means you're fucked) it might be worth looking into as much passive +heal as you can get. ILotP is obviously ludicrously powerful for long fights like this; to that you might add:

[Formula: Enchant Weapon - Battlemaster] / [Formula: Enchant Weapon - Lifeward] (can be enchanted on a spare staff; i plan to get one of these myself, no idea yet which is more healing)

[Invigorating Earthsiege Diamond] (seems at first blush to be about 25% of the healing of ILotP; never used it myself)

[Charged Crystal Focus] (not a potion, so can be used on cooldown; will get expensive quick if you burn them too much though.

Soloing Onyxia as a warrior
At first I didn't really believe it was possible, but managed to nail it after 3 attempts yesterday night.

Spec: I made a special 5/31/35 spec for the occasion, picking up BT from fury and basically any damage reduction talents I could get with the remaining points. Focused Rage from the prot tree is very handy to reduce the cost of BT a bit, since most of the time you're rage starved.
In hindsight I'm pretty sure that any build with BT would do the trick.

Gear: At first I used full tanking gear, but gradually went to getting as much FR as possible. On the successful attempt I had ~250 FR. Furthermore I found that having hit rating and expertise helps alot, since every BT not hitting the boss results in you not getting healed. I used buff food to reach around ~150 hit rating.

Phase 1: Without FR I didn't reach P2 with full health, even when using BT and enraged regeneration on cooldown - the fire damage from the breaths was simply too much. With ~250 resistance, BT alone kept me at full health during all of P1.

Phase 2: This is where it gets dodgy. Needless to say, if you don't have any FR you'll get nuked down very fast by the fireballs. Beyond wearing FR the trick is to use BT on every single cooldown and keep hitting something - be it whelps or Onyxia herself. It's basically a 150 heal on every swing, but it won't do the job alone: Use enraged regeneration every cooldown and bandages whenever possible. To use bandages you have to wait for when Onyxia starts moving. If you got whelps on you, use your fear just before starting to bandage (that's going to be harder if you're specced into deep wounds).
At first I wasted quite some time by running around after whelps, trying to kill them as they spawned. I found it to be better to simply burn down Onyxia until you got 7-8 whelps on you and only switch to them then.

Phase 3: Very easy obviously. If you get through P2 it should be a kill.

(Un)fortunately I forgot to fraps the entire 45 minute fight, and only managed to get the final (and best) part: Onyxia solo on Vimeo

Next time I'll be replacing the tanking gear with some DPS pieces to make it go faster. The physical damage the boss puts out is truly a joke.

I don't know if this is possible even with a pure DPS class like a rogue. You have 100 seconds (60 sec portal, 30 sec banish, 10 secs after banish before beams fire again) to take down 782,460 according to Netherspite - NPC - World of Warcraft, meaning you need 7824 DPS average. Even with the buffs you get from the beams, I don't think it's possible.

2 man should be easy enough.

Just tried soloing a few things myself, as a Protection Paladin of course. Onyxia was easy enough, just took a while to kill. Only used Fire Resistance Aura and went for my regular gear apart from that, Judgement of Light was plenty of healing to keep me in good shape for phases 1 and 3, and for phase 2 I just had to swap to Seal of Light to compensate for her fireball damage, the whelps more than made up for the regeneration I'd otherwise lose from not using Seal of Wisdom.

I went Karazhan next, mostly in the hopes that Attumen would drop his mount. Attumen was easy and uneventful, apart from the curse he does being mildly annoying. Moroes was a bit harder, the Garrote does enough damage to go through my healing from Judgement of Light. I also needed to basically chain stun one of the adds as she was a healer, after the adds that were casters were dealt with I just went for Moroes himself. The remaining add eventually got killed by Hammer of the Righteous bouncing and Holy Shield. It did help to wait with using Divine Shield and Blessing of Protection for clearing Garrote until Moroes vanished, that way you can remove your current Garrote, and he'll reappear without applying a new one. Sacred Shield unfortunately doesn't seem to tick on damage over time, so was basically ineffective for helping with reducing Garrote damage.

Maiden of Virtue was next up, and also wasn't too hard. She did do more damage than both Moroes and Attumen did as a larger part of her damage is magical. She's also pretty bad for your keyboard as Paladin as she's always been as you really need to mash your buttons to get your abilities to go through. She doesn't cast Holy Fire while you're in melee range, though she does use all her other abilities as normal.

For the opera event I had Oz, while I was initially relieved that it wasn't Romulo and Julianne (Which would be just plain impossible with no reliable methods of interrupting Julianne's spells), this was actually a tougher event than I was expecting. Dorothy is surprisingly painful with her 2 second cast time 2000 damage water bolts, and she'll go through your health pretty quick normally. To compensate for that I switched to Frost Resist Aura and used the frost resistance blacksmithing belt. Sacred Shield was also pretty handy to reduce damage done. I nevertheless needed to both use Divine Shield and healing myself up to full and then Lay on Hands just to kill Dorothy, after she was dead the rest of the encounter was easy enough, though it was slightly scary to be stuck on 3k health while Strawman, Roar and Tinhead were still attacking me. Of those three you should definitely kill Strawman first, and Roar next. Tinhead can be easily kited to recover your mana for the Crone, whom is also pretty easy as long as you avoid the tornados.

The content after that I also tried, but didn't succeed in killing anything. For Curator the arcane damage of his Hateful Bolt was simply too high, and while I do have an arcane resist set available, it'd cost me enough armor and block value that it'd make his melee too painful if I use it. Shade of Aran is obviously not an option with the spell vulnerability a Protection Paladin has, and the same surprisingly also counts for Terestrian Illhoof: I never knew he cast Shadow Bolt as often as he did.

Netherspite also wasn't a success for obvious reasons. Surviving him isn't really hard, it's just rather pointless when you can't do enough damage in a single phase and he heals himself up to full on the second phase when you can't have all the beams on you. The chess event could be beaten if you had enough patience to keep retrying, but is pretty hard to solo. I think it's been made harder since it's original version, as I can recall it being easy enough to solo in the past. If I tried using the King piece to primarily do damage he'd invariably die before Medivh's King did, while if I used the Queen piece to do damage I'd usually get the King lower, but Medivh would usually put one of his cheating flame patches where my King was standing, which would take it down too fast for me to deal with.

--

As I'm sure someone is going to ask how you get past Curator without killing him, he needs to be able to see you to aggro you, so if you hug one of the pillars near the doorway to the exit of his room, you can avoid his LoS while he walks past you, and then slip into the doorway once he's at his farthest point away from it. There was little point to me doing as outlined above however, but I figured this might be interesting to know for people who want to try the later bosses in Karazhan without killing Curator.

Has Blizzard removed/altered the hard enrage timers on the TBC bosses? I imagine that these would preclude undermanning the content particularly in T5 and beyond.

Depends what you mean by undermanning. An average 10-man raid now has around the same DPS that an average 25-man raid used to. Soloing or 5-manning stuff will be dodgy, but anything from ten upwards should be fairly trivial. The toughest fights to low-man will be the ones requiring multiple tanks.

Vorpalblade is right about Skeram's earthshocking.
I tried about 15 times to solo him with various tactics, and I do believe it is possible. The split adds won't aggro unless you are near them, so stand on the bottom stairs while tanking Skeram. When he splits engage 1 add with half of your cooldowns and burst it down. When it is down, target Skeram so he doesnt earth shock you and use auto self cast (or clicking the heal while targeting Skeram, then clicking your portrait) to heal up to full. Engage the other add with the other half of your cooldowns.
If you manage that, you can do the whole fight. Unequip your weapon and only autoattack until all your cooldowns are up again (yes, this fight will take a while), while shifting out to heal to full if needed. Repeat the same process for the second and third split.

AQ20 is soloable for a feral druid except ayamis since she is ranged. Every boss drops 2-3 skill books which vendor for 10g on top of the 50-90g the bosses drop. Very worth doing for gold and fun each reset, especially if you want the Got my mind on money achievement.
As is ZG, but people have already mentioned it.

After 3 long hours of trying I finally soloed Skeram, so yes, he most certainly is possible.. at least for a Death Knight. I don't think however that this encounter will be a quick one shot for me every week as there is a huge deal of RNG involved with killing him. I wish I had frapsed it but my computer runs at 5~ FPS as is.

My spec was a cookie cutter 17/0/54 two handed unholy spec in which I was wearing DPS gear in Frost Presence. My glyphs were bone shield, death strike and scourge strike (although I would've opted for the AMS glyph had there been one on the auction house).

Basically what I did was pull him to the base of the stairs leading up to the temple. When he splits the real one will run right for you spamming earth shock and one of the illusions (usually, although rarely both of them come) will come as well. At this point I basically chain AMS, Boneshield, and Ice Bound fortitude together in an attempt to kill the image as quickly as possible (all the while keeping using 100 runic power 3 disease death strikes to hopefully keep my health up). Once the first image is dead I fill up on health, apply diseases to the real one then run to the second illusion to do the same thing I did to the first one. From there it's pretty much rinse/repeat all the while hoping for good RNG, remembering however not to take him to the next 25% interval until all 3 of my short cool downs are up.

RNG can really screw you on this encounter. As I mentioned sometimes both images come which ends in death by earth shock . If either the boss or the image decide to teleport to the section of the temple where the second image is sitting idle it will 9/10 aggro as well, which again will cause a wipe. If you get too many parries while death striking you won't be able to keep yourself up, resulting in most certain death.

I don't know how do-able he is for other classes, but I expect a druid MIGHT be able to do it with nature resistance.

17/0/54 probably wasn't the most ideal spec, but it did get the job done. If I were serious about doing it every week I would probably pick up anti magic zone and make sure I had the AMS glyph (that alone would've made things a lot easier). I am not sure how other DK specs would work out but I think a heavy frost build with both resistance talents might get the job done.

I tried my luck soloing some things on my Prot Pally:

Onyxia - easy. Not much to even really say, this is just an easy way to get ~200g in cash and vendor trash every 5 days for only 20 min of work.

Attumen - also easy, and not much to say. I'm gonna mount farm him every week

Moroes - this one gave me trouble. I tried as Chicken suggested earlier to burn down the caster (it was the healer in this case), then focus on Moroes. But the other adds were the Prot Warrior that disarms, and the Ret Paladin that stuns. The stuns were getting me killed, and the disarms prevented me from getting much returns on seal of light/wis. I ended up just killing all the adds but the MS warrior before forcusing on Moroes. A tip for those interested: a quick Holy Wrath followed by Turn Undead or a heal was helpful, and make sure to keep Sacred Shield up!

Maiden - nothing special. Didn't even need to pop any cooldowns. Silence is annoying, but manageable

Opera - I got BBW, which is absolutely impossible, so my Kara adventures ended here. I may bring someone in to help with BBW so I can get to Curator before the reset.

Lucifron - easy, nothing special

Magmadar - I want to say easy, but good god was this an annoying fight. There was never a time I was in danger, but the fears kept my DPS low and it just took forever.

Gehannas - Couldn't do it - way too much damage. I'm dead before I can even burn down an add. I may try again, but I was tired at this point.

What seal and judgement combo do you generally use Sean? I tend to go JoW/SoV but I'm guessing you must use a combination of Wisdom and Light, because I tend to run out of steam most of the way through bosses.

Edit: Delete.

Solo'd Bloodlord as retribution-spec. When you begin the encounter pull him quickly to where you will be teleporting (that little pool). When you get MC'd, if you end up getting teleported, he will be standing right in front of the pool for you to attack so that you don't end up having him reset on you. Never had any fight resets if I did this, though be careful not to blow a big-raged attack on him immediately after MC as he evade bugs for a second or two after the MC wears off (I was personally having this problem).

Just fight Jindo in the skeleton pit.

Stop calling him bloodlord, that's the raptor boss. You are talking about jin'do.
The reset occurs when he charms you at the same time as he teleports. He will reset regardless of where you stand. The only thing you can do to affect it is wear full dps gear, go cat form/blood presence/berserker stance since you will heal to full every 20 seconds anyway.

After 10 attempts today I managed to kill him too. I tanked him exactly where he starts.
The last split images have alot more health than the first, so i only killed 1 while saving cooldowns in case of a bad teleport. He didn't though and the other image despawned when Skeram died.
I didn't use nature resist. It is probably a good idea. Without nature resist you need very good gear.

With new found self esteem I went down Sartura's tunnel, having to kill all the mobs since they see stealth. Used berserk and every other cooldown available on Sartura's adds and managed to get them down when I was out of cooldowns and on 6k health. Bark skin + heal up and from there I had to go caster to heal about every 2 minutes and she eventually died. I don't know if I got lucky since it was my first attempt. Demo roar helps very much, reducing her melee by 25%. [Essence of Gossamer] is also very good since her whirlwind hits twice a second.

The Ruins of Ahn'qiraj are (largely) soloable as well as a Protection Paladin, though there are a few things to note.

Kurinaxx and General Rajaxx are both not particularly notable. The only thing to keep in mind for Kurinaxx is to keep moving to avoid the Sand Traps. General Rajaxx just takes a while to kill.

For Moam you'll need to do so some Seal and Judgement switching. To start with, use Seal and Judgement of Wisdom to compensate the mana drains every few seconds. When Moam spawns his adds, switch to Seal and Judgement of Light, as you'll soon take a big damage burst from Moam getting to full mana. While his adds are up mana is a non-issue, so keep using Seal and Judgement of Light until they die, then swap back to Seal and Judgement of Wisdom. The adds are not at all threatening, so simply continue directly attacking Moam and counting on Hammer of the Righteous and Holy Shield to take down the adds eventually.

For Ossirian I found he hit too hard to solo while not using his crystals. This means it's necesarry to clear his trash as well, the only time the Anubisaths are threatening is when they have Meteor. I used Fire Resistance Aura and swapped my usual Seal of Wisdom for Seal of Light if it was an Anubisath with Meteor. After clearing Ossirian himself is easy enough to kill, though slightly tiring as you have to keep moving him from crystal to crystal while also scouting for crystals yourself.

Buru the Gorger is doable as well, though rather annoying to kill. The hard part lies in getting the first 80% of his health down, it's easy after that. Each egg you kill on top of him seems to do about 5% damage, so this takes a while. The remaining 20% health after that is easy enough to get down, especially as you have plenty of adds on you to keep your mana up.

Ayamiss is impossible to kill due to a lack of ranged attacks and the fact that her damage is largely magical during the first phase.

Finally there is one particular trash mob worth noting, which is the Flesh Hunter slimes. These are not killable while in melee or Judgement range, as they will at some point cast Consume, stunning you for 15 seconds and dealing 3000 damage every second, this is also an ability you can not use Divine Shield to get out of. Past Judgement range this ability is not used, but the mob is obviously rather hard to kill this way.

Mage solos Military Wing in Naxx. I would say thats a nice little feat, even though its completely broken and will get nerfed.

YouTube - Naxx Heroic Military Wing soloed Mage

That's possibly the most hysterically awesome thing I've seen yet in WoW. And it's even better because it's a female gnome.

I use Seal of Wisdom/Light depending on the situation, and always Judge Light. I'm using SoW primarily, unless I'm taking too much damage or am getting hit by enough mobs to get plenty of mana. JoL will keep me up in most situations, but sometimes the damage is just too high and I need to SoL. For example, I used light for most of the time on Moroes to keep me alive long enough to burn down the adds that were giving me trouble.

Even with SoW, mana is still a struggle on most bosses. I just always try to have enough mana for Holy Shield and Sacred Shield - so long as you have those, you're in good shape and can slowly auto attack down a boss.

If you're running out of steam on Onyxia for example, try to keep some whelps alive for the mana returns, or even pull some out of the caves.

Just did AQ20 as well as a DK. I'm blood DPS specced which isn't optimal, and I died a few times here and there (don't touch the slimes near Buru ), but the next run should be wipe free. Killed everything except Ayamiss, and none if it was really difficult except the trash at Ossirian.
Like the above poster said, they're not really a threat unless they have meteor. What I did to kill them was use IBF and AMS and hope for some lucky timing. With enough DPS you should get it down before he casts a 3rd meteor (I was in tank gear mostly, so it should be easy).
Ossirian himself can hit pretty hard, so I pulled him mounted and dragged him to the first crystal. I found that if you just kite him in circles around the room, you'll always have a crystal to debuff him on time.

Pretty fun all in all, and the tomes/books/manuals sell for 10g at the vendor, which is great .

Was very quickly nerfed. The bone shield can no longer be spell-stolen from the Cavaliers.