Okay, if your guild is on Eredar Twins or you have read about the boss you will love this trick, it makes the fight a lot easier. Read about them (Eredar Twins - WoWWiki - Your guide to the World of Warcraft).
The trick works best when Grand Warlock Alythess is killed first (most common).
Lady Sacrolash gets misdirected to tanks on top of the platform/balcony standing on the edge getting healed from healers down on the floor.
Very common tactic, but there are some downsides, tank up on the edge doesn’t get their Dark Touched debuff reset
(Dark Touched: Healing effects reduced by 5%. Stacks up to 20 times, or a maximum of 100% healing reduction for 3 minutes. Any Fire damage taken removes the effect)
Normally the offtank (tanking changes all the time) then would have to jump down and step in to some fire to remove the debuff. This Is very risky, and a lot could and will go wrong that way.
This I where the trick come very handy!
Seconds before the pull, a warlock with the two tanks run up on the balcony and step just outside the room. Then they summom a infernal! (Inferno - Thottbot: World of Warcraft), and the tanks make as much agro as possible on the infernal without doing any dmg to it (sunderarmor with a gray weapon).
Pull the twins and the infernal will stick to the tanks on the balcony with its aura doing 200fire damage every 2sec or something like that, and WOLA tanks don’t have to jump down and reset debuffs. Makes the fight a lot easier!
Hope that will help some guildsuntil it gets nurfed