Considering I've been gearing myself up to be one of our "lock tanks" for this fight I thought I'd share some of my knowledge of the basic strats for this fight.. This is not a standard "tank & spank" fight and if people aren't on top of their game for this fight it will not work. My suggestion is read what I'll be posting but don't take it as gospel, google the fight, read other strats, watch videos, talk to ppl you know who have done the fight and be prepared to listen to other people's advice. There is no reason we can't down this boss before WoTLK. Personally, i can't wait to give it a go :)

Here's what I've found to be most useful to me:
Leotheras the Blind

Whirlwind - Human form - Leotheras starts spinning uncontrollably in the room between random targets for 12 seconds. Instantly deals 3k physical damage and also applies a DoT that deals 2,5k damage every 3 seconds for 15 seconds. A complete aggro wipe takes place once the Whirlwind is over.

Chaos Blast - Demon form - Deals a small amount of fire damage but also applies a debuff, that stacks up to 20 times, that increases fire damage taken by 1675. The damage splashes to nearby targets.

Insidious Whisper - Demon form - 3 - 5 random targets get the Insidious Whisper debuff. Each player affected by the debuff has 30s to kill a demon that spawns or they end up getting permanently mind controlled. Only the effected player of each demon can harm their respective demon. Currently this debuff is somewhat bugged, if a pet or totem belonging to the affected player gets the killing blow of the demon the player will get mind controlled even though the demon is dead at the end of the debuff.

Enrage - After 10 minutes Leotheras enrages and wipes the raid with the help of a severely improved Whirlwind.
Phase 1

Humanoid Phase, lasts about 40 seconds. The first Phase 1 begins by pulling the 3 adds banishing Leotheras. Each of them needs to be tanked and killed. They do 3k Mind Blasts with 10-15 yards AoE effect to random people in the raid every few seconds. Each of them will banish up to 1 player at a time, for a total of 3 players. They'll keep banishing random people until they're dead. They're nothing serious.

After the adds are dead, Leotheras will become active in his humanoid form (this is the point from which the 1 minute phase duration is counted). He should be Misdirected to the main tank who's waiting at the tanking spot.

About 15 seconds after the beginning of the fight he will reset his aggro and start to Whirlwind around for about 10 seconds. You need to be spread out and keep moving away from him to avoid getting hit. Be very careful when healing in this phase as you do not want to accumulate much aggro on Leotheras and have him kill you once he's done Whirlwinding. If you're a non-healer do not drink any healing potions so as not to risk getting any aggro on him. The tank needs to follow him around and grab him as soon as he's out of the Whirlwind and accumulate aggro. Nobody attacks him for at least 5-6 seconds after he's stopped so the tank can hold aggro. 15 seconds after he's stopped the first Whirlwind he'll do another Whirlwind. He will turn into his Demon Form while he's doing his second Whirlwind.

Bleeding : anyone hit by the Whirlwind will receive a bleed effect which will result in a certain death if you are not healed fast. The dot can be removed with Divine Protection, Blessing of Protection, Ice Block or Dwarven Racial Stoneform.

Have a hunter to misdirect your tank after the Whirlwind it will avoid people dying and will allow you to DPS faster.

Phase 2

Demon Phase, lasts about 60 seconds.Leotheras turns into a demon and remains stationary while shooting out Chaos Blasts on his target. In this phase, it is recommended that a warlock (preferably with soul-link) tanks Leotheras from range so that melee DPS can still attack him without being hit by Chaos Blast.

The warlock should use Searing Pain to grab and hold aggro on Leotheras. It doesn't really matter where the warlock stands as long as it is clear of Leotheras and there isn't anyone in a 10-15 yard range of him. Everyone needs to be well clear of the tank to avoid being hit by Chaos Blast, which Leotheras will start casting on the warlock. 15 seconds into the phase, he'll summon Inner Demons for some random people, and they will have to kill their own Inner Demon. What you need to pay attention to with Inner Demons is (edit - I don't know if the following is still relevant but most posts I've read have mentioned this):

* Hunters: it can be hard for hunters to kill their demon on time since the demons are melee, and hunters have a deathzone. pets can be usued against demons but if the pet get the killing blow the hunter will get mind controlled, use your pet with growl on, dps the demon all the way down to 20%, then click on pet passive and stay, so the pet stops attacking and stays on range holding the mob for you, 3 more shots should be enough to finish the demons.
* Priests(holy): all priest should wear atleast 300 spell damage, or they will have it hard killing their demon, start with with a dot, PW:shiled and Smite them to death. SW: death is also usefull, you should also have someone else to heal you since you have to focus on kill the demon.
* Druids(resto): Use some spell damage gear, demons get extra damage from Nature Damage, Use Insect Swarm if you have it, and spam Wrath
* All other DPS classes should be able to kill their demon easily
* Pets. If you use any class of pet make sure it doesnt get the killing blow, or your will be mindcontrolled even if you killed your demon on time.

After the 60 seconds are over, he'll go back into his humanoid form.

He will rotate between Phases 1 and 2 until he's at 15%. This is when Phase 3 starts.

Phase 3

Humanoid and Demon Phase.At 15%, his demon form will split from his humanoid form, leaving you with 2 bosses to fight. His demon form needs to be tanked again by the offtank warlock, with nobody in a 15 yard range of the warlock. His demon form will be the same as in Phase 2, except he won't do Inner Demon anymore. His humanoid form needs to be tanked by the main tank warrior again and it will act the same way as in Phase 1, opening with a Whirlwind and repeating it every 15 seconds just like in Phase 1. However, you won't really have enough time/survivability to see more than 2-3 Whirlwinds no matter what you do. You need to nuke down his humanoid form as fast as you can, as he will be near his enrage point now. As soon as his humanoid form dies, the fight is over and the demon form vanishes.

Yes, it's technically challenging and requires precise management of threat and dps but seeing how well Shadow Warlords have done since I've joined I can't wait to be standing there over his dead body while we all hand out his phat lewtz!! Thanx for reading :)

Nice run down mate. =)

I was talking with a friend of mine over the weekend about this fight. I don't know if it will help us out at all or is something we may want to try, but, for their guild, when the aggro resets, they have a shaman lay a searing totem in the middle of the room to get initial aggro from Leo and lets a tank pick him up. Thought it may be something interesting we could try :)

yeah, i've read the same thing but not knowing enough about shamans i thought it best not to open my mouth & look like a retard if what i was saying was wrong lol..

i would've thought hunter MD would work as well..

meh, what do i know lol..

A hunter misdirect would be good for making sure that the tank reacquires solid aggro, the idea behind the totem is that it draws Leo toward a specific location without anyone taking action, so he's kept away from the group.