Strategy - Blood Princes

After doing quite a bit of research this morning, it seems like any tank can tank Keleseth now that he no longer melees his tank.  However, in 10 man, it may not be a luxury that you've got 3 tanking classes available, and the warlock class is really the best suited to do this fight as a range tank.  Any of the 3 PvE specs will work, but I'll discuss them below:

All specs:  The pet of choice should be the Felhunter (10% magic damage mitigation) or the Voidwalker (damage absorbing shell).  Most sites suggest the use of the felhunter over the voidwalker.  All specs should be putting their demonic circle in the middle of the room so that they can port there to be in range of more dark nuclei as they spawn.  The warlock tank needs to have at least 4 on them when Keleseth is empowered, preferably as many as possible at all times.  Any less than 4 and it might get dicey.  Keep nameplates on in your UI to easily identify the orb targets, and use Curse of Agony rank 1 to pull orbs to you.  Since the orbs die over time, using the rank 1 Curse keeps them alive longer, and will keep aggro as long as other folks aren't beating on them.  Keep Keleseth as your focus target and create a macro that casts Searing Pain (1.5 threat generation scale with that spell) on your focus target.  Make sure Curse of Elements is always up on Keleseth (+ 13% Magic damage and reduced resistances).  Use Demon Armor instead of Fel Armor as it gives a bonus to armor, and increases healing done to you (making it easier for our healers to keep you up).  Also keep Shadow Ward up, especially when Keleseth is empowered to help with the damage mitigation.

Demo:  Really (in my opinion) the best spec to tank Keleseth with.  There are specialty specs that are PvP-PvE hybrids out there, but since the change to his melee and Hellscream's buff, it doesn't seem that they are really all that necessary anymore.  If we struggle, it is an option to go to.  Demo gets an additional 20% damage reduction through Soul Link (30% total if the pet is Felhunter, (+ damage shield if Voidy)) as long as our pet is up,  so healers need to make sure that it remains so.  Shouldn't be tough, as it shouldn't be taking much damage, but keep an eye on it for us.  The Fel Synergy talent helps Demo locks do some of this already.  When in Meta form, our armor is increased by 600%, and we get taunt to use (Challenging Howl) to make sure bloodlust doesn't pull Keleseth off of us.  Timing of Meta during bloodlust is key if it is off of cooldown at the time.

Destro:  Pretty much the same idea as Demo, except that it might be a good idea to spec for Nether Protection, and Molten Skin.  Not as consistent as Demo mitigation abilities as NP is based on a % chance to proc, but when it does, much higher damage mitigation.  So, if the RNG gods are kind, could potentially be a better spec than Demo, but if not, get ready to clean up the mess.  :)

Affliction:  Probably the last choice.  Afflocks get a lot of healing through talents like Soul Siphon and Siphon Life, and if you are running with the Never Melting Ice Crystal and can keep rolling corruption on Keleseth, threat will not be a problem for you.  Damage mitigation, however, is weak in most affliction PvE specs.  Really need to reach into the Demo tree for Soul link to make affliction most viable here.  Lots of articles on a number of sites that says a skilled afflock will be able to pull this off.  As I am not one of those (even though it is my off-spec), do not choose me unless you find me dying repeatedly amusing.  I do not.  :)

Seems like 30k health (raid buffed in 10-man) is the magic number we're looking for here.  If you can't get to that, a couple pieces of PvP gear may do the trick for you.  I think both Hecetaus and I are there, may be a couple more as well. 

On a side note, I've seen that frost mages may be able to do as well here since the nerf, so if we don't have a lock, we usually have a mage.  Again assuming that we don't choose to have a regular tank class do this.  (Death Knoghts might be a good choice too, but I didn't research any specifics about them in particular).

So, that's where I am at with it.  I think some discussion by the raid leaders would be good.  Maybe I'm missing something from another class's perspective.  Comments welcome!