After my first foray into there, I'd like to warn you all about potential wipes that we ran headfirst into...
1st Wipe - When you are clearing adds on the way to the bosses, watch out for 'Spiteful Spirits' - the floating skulls that are targetable - and SPREAD OUT! these guys target a random player and blow up (I think its 15 yards) for about 8k damage on mail. we were all buncheed up on a bad pull and these buggers blew up our healer. we didn't last long after that.
2nd Wipe: 1st Boss, Yadayada, Grandfather of Souls (or summat) - This guy bears a striking resemblance to Noth... Anyway... he has 2 phases to worry about. at first, he will randomly target a (non-tanking) player with 'Corrupt Soul'. when you are hit by this, you and the tank must RUN to opposite sides of the circle-arena-thingamajig you're in. After the effect ends, the targeted player will be stunned and a orb called 'Dark Soul Fragment'. This orb needs to be DPS'd immediately, and the tank needs to try and keep it away from the granddaddy. if it gets to him, you still have ~2 seconds to DPS the orb before he casts something that looked like 'Evocation' and consumes the orb, healing to full. (note - the tank CAN pull him away from the orb during the 2 seconds, but can't pull if he's already consuming.)
We didnt realise that 'till the healer was OOM.
3rd Wipe: Grampa Yadayada, again. Phase 2: Soul Storm (roughly 15%) He'll emote and you'll see a torrent of souls (that looks suspiciously like a flushed toilet) swirlin' round the edge of the room. this is everyone's cue to move up and hug him, as you'll be taking damage if you're in the perimeter. Hunters CAN back up a wee bit to keep shooting, but be careful.
Healer must've been having a bad day... death by the Soul Storm.
4th Wipe: 2nd Boss - Devourer of Souls: She/He/It/They (NOT going to use an acronym, tyvm) appears to target a random player and open up a pink void zone under them that causes damage over time... right before he jumps on their head (12k damage on mail). ranged needs to spread out (and run when it appears).
Me and healer died.
We got him on the fifth, but I'll explain the rest.
He also has a nasty little ability called Mirrored Soul - It reflects all damage delivered by a targeted player. It can be as easy as stopping shooting, but DOTs on the boss WILL tick against you, so the healer needs to watch this. For hunters, I would recomend throwing a viper/wyvern sting on to remove the serpent sting(that really hurts.) Affliction warlocks will NOT like this fight.
DoS will continue doing the above throughout the fight. he will also randomly switch faces on you.
(Face Of Many Adds) - Summons several untargetable adds. if the healer can't heal through it (looking at you, cross-realm priest), everyone who can needs to try and kite them around and take as little damage as possible while the healer concentrates on the tank.
(Face Of Shadow Bolt) - Casts a bolt of (insert element here - cant recall it) at the tank periodically. Can be interupted.
I think there was another face, but memory slips. if anyone knows of anything I missed, post here.
Now to go do it again because the healer wouldnt rez me at the end of the fight... I didn't finish the attunement quest.
(KEEP IN MIND, THIS WAS ON NORMAL)