There is a fair amount of trash through here, but nothing overwhelming. Main trash to the first boss just interrupt casts, no CC needed. The bigger elementals are the more threatening. Before the first boss there are 2 of these elementals. Keep constant interrupts up and you will win. Elapsed said you can use Turn Evil on them, but that and Banish I think are the only things you can use on them. They do pat into a room, so you can bypass them if you want to wait.
First boss, Sadana Bloodfury, isnt too bad. Just make sure you do NOT step on the purple runes on the ground. She will summon a dagger above a random player, move out of it. It will do aoe dmg to players nearby so just avoid it once its on the ground. She will summon a spirit add, stun it and kill it. If it reaches her it will heal her for 25% of max health and give a dmg boost. She will run to the middle of the room and summon an eclipse that deals massive dmg. To negate this dmg, stand on one of the highlighted moon runes on the ground (see vid) and it will reduce the dmg by 80%.
Trash to the 2nd boss can be a pain. There are adds that constantly channel a rend type ability on players, focus these adds and keep them interrupted/cc'd. If one player gets tag-teamed by 2 rends, they will likely die. Also stay away from the square graves on the ground, adds will spawn from these if you get too close. This comes into play in the next boss encounter.
Second Boss, Nhallish, is fairly simple, but if you arent quick during the phased part, you will die. Keep the boss faced away from the group, he will channel a frontal cone ability that will follow you if you try to strafe out of it, so tanks just need to sit there, pop a minor cd and deal with it. He will teleport to a random target, and channel a whirlwind/vacuum. Run out of this, once you get so far away you wont be pulled in any further. He will send you to a phased realm and separate your spirit from you. You need to kill your spirit and click on the remains to get out of the phase. If you do not kill it within 20 secs you will die. The spirit will constantly run away from you so use slows or stuns to help out. Healers be sure you have your offensive spells on your bars for this. He will also shoot lots of shadow missiles into the air that crash to the ground and leave void zones. These are easily avoidable and will despawn over time. Stay away from the outside of the room to avoid spawning adds from the square graves I mentioned before.
Trash to 3rd boss can be rough. Use CCs on the casters and kill them one by one to make life easier or you will get overwhelmed with adds. After those you will have bats and spiders to deal with. The bats are too big of a deal, but the spiders can kill the tank relatively quick with their poison. They have 2 attacks and one of which applies a debuff and REALLY hurts on the application. Cannot remember the name of that ability, but that is the priority to interrupt. On the long bridge to the boss there are bats and a giant worm that will spawn (similar to the lava worms leading to Rag in Firelands). Try to range pull the bats and kill them before spawning the worm. Tank stay in melee range of the worm and dont get hit by slam. If you get knocked in the water, use the blue water jets coming from the water to get back to the platform.
3rd boss Bonemaw, was kind of a pain the first time Elapsed and I ran it, but was easier with a guild group. Tank the boss facing to the side of the platform to keep his slam from hitting the group. He will use "Inhale" to suck you into his mouth to eat you. When the notifcation for this comes up, run to the other side of the platform and start running away to avoid being pulled in. The pull gets stronger near the end of the cast/channel. He will spawn death zones on the ground, itll just look like a circle with skeleton arms grabbing around at you, if you are having a hard time running away from the Inhale, you can stand in these and it will root you in place, BUT you will take a lot of dmg being in them. Its easier just to run away. After the first Inhale he will spawn back his 2 worms from trash you fought earlier. You need to have 2 other players in melee range of them or they will spam cast poison on to the group and kill you. Try to keep them facing away from the middle of the room so the slams from both of them and the boss do not cover the entire platform. If the slam positioning is bad and there is nowhere to stand, JUMP off the platform and swim to the water jet thing to get back to the platform quickly. Focus the smaller worms then back on the boss. Once the smaller worms are dead, the boss will randomly change his position from his main place to one of the other 2 worm spawn locations. Nothing changes in regards to the fight overall, abilities all remain the same, just the positioning is different.
Trash to last boss is just a 2 spider, 2 bat pack. Then a 2 elemental pack before the door.
Last boss is overtuned and we were not able to kill it. It would be best to watch the video to understand what goes on. Primarily just keep him faced away from the group. He will always cast his big dmg-ing ability towards the tank, which leaves a large corruption line on the ground for a few seconds, and will always drop his shadow orb (pulses AoE dmg) on the tank, so there is always a lot of repositioning for the tank. The skeleton add line needs to be dealt with as soon as it spawns, kill one skeleton to break a hole in the line for the group to move through. Touching the skeletons or the shadow corruption behind it is a one-shot. The big thing with this is the constant group dmg going out that really screws with a healer. That and the timing of the abilities, the tank has to be REALLY quick to time when he uses his shadow line and orb ability to be able to get through the hole so he doesnt drop either of those in the middle of the group and wipe them. You can see what I mean by the vid. At the end the timing was bad and the line got dropped right down the middle of the escape path. It was a wipe by that time anyways, but thats the frequent issue that kept arising during our attempts. A bit overtuned for a normal.