Since I plan on PuGing LoB again pretty soon on my cleric I thought I'de share my experience on this new raid for those who haven't done it yet:
First thing first "Don't Panic", yes the sources of damage are many, yes they all hit for at
least 90/100, yes people will die and yes you'll need to drink pots.
Roles:
The way we did this required 3 healers: 1st on the main tank, 2nd on the replacement tank and 3rd on the party.
1st's job is "simple" keep the tank alive at all times, give FoM and Resist elec when he dies and use Unyielding after his 3rd/4th death to keep his HP above 700 which is pretty much the minimum to tank Blades.
2nd's job is the same as the 1st's, but you'll also be the default resser, why? The 2 others don't have the time to stop healing to ress someone, if they do more *dings* will occur. Why 2 tanks? Blades like to de-buff HP so the tanks will need to rotate until it goes away. Also be ready to drop mass cures on the party to help the 3rd healer.
3rd's job is to keep the party alive with heals centered on him, the healer with most HP gets this job which is not at all easy for reasons that'll come up a bit later.
Blades phases and attacks:
The name of the game is staying together, save the caster and the 1st and 2nd healer everyone else absolutely needs to be close to each other so mass cures are not wasted/ineffective.
The fight has 2 hounds that provide 25% DR each to Blades and need to be taken down ASAP, not only because of the DR but also because of the damage their "Goo" does, think Grease with no knockdown but 90/100 ticks or untyped damage, most of the *dings* will come from this. After they are down you get to pound on Blades, but from the back only he has a Cleave attack that deals around 600 damage and when he stuns the tank he does a Whirlwind attack for the same amount, basically only the tank should be in front of him and when he yells "Stunned!" run away. When he's taken enough damage he will leap upward and drop blades on those who are static, when someone says "Leap!" run around, when the center glows run to it and use Bursts to remove negative lvls and top off the party and try to grab the buff that allows to destroy pillars, or at least make sure the boss doesn't get it (everyone try to get there 1st).
Next phases, same thing as before until he goes down to 5% then it gets hard, he'll go bezerk attack faster and 12 or so assassins with repeaters will appear, these re-spawn and our PM had to run around spamming Wail to keep them from killing the party (they have **** fort saves thank God), Kill puppies, go to town on Blades and then it's pillars time.
Range attackers go for them from the center while at least 4/5 melee and healers stay there to deal with the monsters spawned, there is a timer on this so be quick.
After, divide the party in 4 to kill some elementals for your spirits, make sure all 3 are in the platform when you speak to the stone or they will be locked out of that room, after that fight you just won they might as well be empty crates by the way.
What not to do, what to do and have ready:
Resurrection/True Resurrection scrolls only, Goo will kill most players so returning with a sliver of HP will get them killed again, or worse yourself trying to heal them after a ress so Raise Dead is useless.
Mass-Heal is too slow, even on Quicken the fight moves around too much.
Kiting: do not kite, this was the reason our 1st try failed. Infective masses means death here and pretty quick, either pew pew from melee range or switch to melee weapons.
Keep him tanked, Blades has a "Dashing attack" that knocks down, this plus the hounds Goo will kill anyone that gets caught, the hounds need to be killed away from the boss.
No DoTs, after his Leap he'll go after the DoTer, if it's a healer you just put the whole party in danger.
Metas to spells: have Mass moderate/serious/critical with Max on, True resurrection and Heal on quicken. Heal tanks when around 2/3 HP, heck as soon as they are hit is not wrong either.
DI is not an option, damage is constant and he'll die anyway.
Have the following on hot bars: Resurrection/True resurrection scrolls, Pots and lots of them, FoM and Resist for your tank, Unyielding and Burst/Auras.
Drink pots any time you get half a second of rest, damage numbers are pretty big and you don't get many moments to rest.
Tanks with voice are a must have to know when Blades is about to do something nasty, same for calling "Goo" which is pale green on top of pale blue so kinda hard to see and can lead to death.
Hope this helps, and please add any strategies I might have forgotten or any other spells/items us healers should have loaded.