The event involves the following events...
1. Clear mobs up to the sisters area and clear the immediate area of mobs (not the east wing yet)
2. Pull the 6 mezzable bats down from the west wing and get the chanters to lock them down (the east side of the big room seems to work best).
3. Pull the east wing having your puller avoid the bats so that the pallies (who help position the mezzable bats) and the chanters don't get agro. You pull the east wing last so that those respawns won't be a problem right away once you start the event.
4. Now have your rogues/monks find the 3 sisters in the west wing. They will do the hailing first. You start the event and they start the hails (will get to that next). Once they start the event you have a whole bunch of mobs pop in the west wing. Pull them all.. and get them cleared as fast as possible.
5. When west wing is cleared you move your hail team up to the west wing. Your teams need to be composed of the hailers, extra hailers and curers/healers.
Hail Team
Each sister is looking to undo the other sister. You have a hailer follow them and hail in /say. You will get two messages. One in blue text tells you what she is doing and there will be an all caps word (or two) in that message. This is what that particular sister is doing (there are 3 sisters Althea, Brenad and Christine (ABC)). The second message you get right after that is in /say and she asks what one of the other sisters is doing.
So you may get a blue message with something that says "blah blah blah blah POISONOUS SUBSTANCE blah blah blah" and then right after that something like "althea says, What is Christine doing?"
The other hailers will say in the special channel what each sister is doing. If christine is "Dead Rats" then you have althea targeted and you simply "/say dead rats". If you are successful you will get a yellow text saying that you have successfully incriminated christine.
You have to successfully incriminate 2 of the sisters 10 times.
Every two minutes the sisters move (you get a message that they are getting ready to move) at which time you can do another hail and another incriminate.
Some things to worry about....
If you are a hailer then you are going to get other yellow messages about how you can't hide.. blah blah blah.. but it ends up you getting Dotted. You need to get cured asap because it is nasty. Usually you will have a cleric and/or shaman following you (or standing in the main hall where you can go back) and can cure you when you tell them you are dotted. This is very important.. IF YOU DIE YOU CAN NO LONGER HAIL A SISTER.. you are officially off of the hail team at that point. One of the backup hailers now has to take your place.
Another thing to worry about is that you cannot hail more than one sister. Once you have hailed a sister and gotten a message then you are locked on to that sister. So your back up hailers do not hail anyone until a primary hailer is dead.
Finally, when the sisters are close together then one will likely overhear someone giving a /say to a different sister and you won't get a successful incriminate. This is what makes the event challenging since you are timed. You get 25 minutes to complete the task with being able to hail a sister every 2 minutes. So you have to try and get to maximum hail distance to /say something to try and avoid one of the sisters nearby from hearing as well.
There are 9 different hail messages you can get... Poisonous substance, dead rats, spying, crying softly, scoping, and a few more i can't remember
.. but you will have to make hotkeys for all of them that go to your special channel so that they know what your sister is doing so they can incriminate her if their sister asks what she is doing. A typical hotkey looks like ..
/3 Althea is ... SCOPING
If you get 2 sisters incriminated 10 times then you win.. and all the mobs in the area depop including the bats that are being mezzed. If you fail you have to kill the bats.
6. While you are doing this the rest of the raid sits at the door of the main room. The east wing will repop during this time and you have someone pull those mobs and kill them since sometimes the sisters will roam over there.
7. About 20 minutes after the event has been popped you need to move the entire raid up to the west wing because the west wing mobs will start to repop too. Have pullers pull them and the hail team just continues doing what it is doing. If you are good enough you can finish the event before west wing repops but often they do. If you finish with a success while they are repoping they will simply depop.
The End....
Footnote: Finding the sisters can sometimes be tough. Of course with MQ finding them is trivial but for the rest of the raid that doesn't use MQ they will need trackers (or the pet trick listed above) to find them since they warp from area to area. On your DPoB map of the west wing there are 7 rooms and 2 basements. Name your rooms 1-7 and your NB (north basement) and SB (south basement)... if you see one of the sisters that is not yours you can tell the channel where she is. They do occasionally come out and start to go east as well.
Last footnote: The doors to the rooms randomly lock and you can't pick them. When you get the message that the sisters are about to move all of the doors open and you can move through them then but once they close most of them are locked. On the south side there is a secret door (should be on map) that never locks and on the north side the center door never locks so those are the ways to get to the north and south basements in a hurry.
Anyway, it is a lot of info.. you will fail several times until the hail teams get comfortable with it and then after that it is pretty easy and you will hardly ever fail and when you do it is usually due to just bad luck.