First things first... trash is by far the hardest part of this instance, much more so than the bosses.  That MIGHT change on heroic, but I doubt it.

The Arrakoa trash are very annoying and you need to CC them to make life easier.  Some will heal (I think those are "east" Arrakoa), some will sit there and mass dispel all the CC you have done if you leave them up... some will empower the others.. its just a shitload of bad news.  Once we re-run this on heroic Ill make anote of the names of the trash packs and what they do so you can better prioritize your CCs.  Just know, you will need CCs.

The first boss Ranjit sounds a lot harder than he really is.  He will randomly charge players and deal light/moderate damage.  His main mechanic to be aware of, is he will throw a white spinning blade at a random player, this hurts a lot.  After it lands it will spread out into a line of spinning blades, and that line will rotate either clockwise or counterclockwise (think of the lightning orb hallway in the new Heroic Deadmines that insta killed you).  These deal heavy damage, but thankfully they rotate very slow.  After 2 sets of those are sent out, he will summong a 2 fiery arching lines that cross the platform and spin either direction again.  This will force you to move around the platform and with some bad positioning of the group and the white spinning blade lines, will make you have to go through them to "live".  But like I said, thankfully these all move really slow so as long as you are alert, you shouldnt have a problem.  One thing that does suck is while the 2 fire lines are out, he will still cast additional white spinning blades on players, so it just filles up the platform faster until the fire line despawns.  Take note,  the blades can and will change their spinning direction at any time, so you may have to backtrack.

After this boss is my "favorite" add.  I say this because its a piece of shit!  At the top of stairs there will be a large raven add running back and forth between 2 packs of trash.  No big deal right?  WRONG!  First night we tackled him, I charged to the top of the stairs and tried tanking him between the 2 packs of adds.  He flipped me over behind him, and then knocked me back into one of the trash packs.  THEN he charged me, flipped me over again, and knocked me back into the OTHER trash pack.  Sure it was funny and lots of "fucking knock it off bird!" was called out in mumble.... but it sucked.  Best thing to do with that bird is pull it down the stairs to the main platform and kill it there, but be aware, that POS will do his damnedest to knock you up the stairs and into those trash packs.  After the bird is dead, you can pull either the left or right side trash packs.  Just pull them down the stairs and CC appropriately as they approach and kill.

Second boss Araknath is very underwhelming.  He only has a few abilities, but it can last a while if you dont execute the fight properly.  He does a smash ability on the tank that he does with either of his arms, so melee just stand directly behind him so they dont get hit with it.  He also does "Burst" which is a light/moderate AoE that increases in dmg with each cast of it he does.  Is not interruptable.  The main mechanic that drags this fight out is the "Energize"  Sunlight lines will shoot down into the mechanicals around the room and shoot to the boss and restore his health.  You have to stand in them to intercept the line, but this will cause ticking fire dmg that increases the longer you stay in it.  So you CAN take one in its entirety (we did), but you might want to rotate people out.

Next trash pack, just pull the bird packs separately because they will randomly focus people, if you pull both packs together and they all RNG and focus one person, GG, dead and it just spirals out of control from there.

Third boss Rukhran is a stationary fiery Raven.  He will use an attack on the tank that stacks fairly frequently.  You can use active mitigation to prevent these stacks from applying (I just used Shield Barrier when he hit me with it and that worked fine).  He will launch out solar flares that will deal light/moderate dmg to anyone within 5 yards of impact.  He will also spawn phoenix adds that will focus a player and follow them around.  The phoenix adds move really slow and you CAN kite them the entire fight if you so choose, but early it itd be best to kill them off.  Key note on the phoenix adds, is that once they die, they will leave a pile of ash on the ground.  If a solar flare lands near them, they will re-ignite and the add will reappear.  And if you kill a phoenix add near a pile of ash, the explosion they do deals high dmg to anyone within 10 yards, but will also reignite the ash pile.  So kill them away from each other.

You will have a wind gauntlet you have to run after this boss up to the next main platform, during this wind gauntlet you are constantly pushed back while raven adds peck at you from the sides dealing 10k dmg to you each time they hit you.  Stampeding Roar helps get through it quicker.  In the big room before the final boss you will come across mechanical adds.  The large one deals decent dmg, the reflector one puts shields on everyone, and there is another that empowers all of them.  Trap, root, CC them however you can and just kill them one at a time.  There is also a large Arrakoa add with them that can easily wipe your group with a supernova ability, be very cautious with him as he will disorient you and hit you with it.

Last boss High Sage Viryx brings back some memories from Wrath days.  He will target a player with a laser that you need to kite around the platform and will leave fire patches in its wake.  Kite smartly.  He will summon arrakoa birds down to pick you up and carry you over the edge of the platform and drop you to your death (think back to Lich King Valkrys in P2), these can be stunned and slowed..  Lastly he will summon a mechanical shielding add to put an immunity shield on him.  This shield is interruptable, so you can interrupt it and get extra cleave dmg on the boss while you focus the add down, or you can just focus the boss, and cleave the add down while interrupting the shield.  Its a pretty simple fight, just try to stay out of fire, kite smart, and focus adds quickly and you win.