WORK IN PROGRESS! Lots of guessing and incomplete data. Proper version will take a while because I'm really busy with IRL stuff. If you wish to help please let me know.
Gorseval is the second boss and has a much tighter enrage timer.
He appears on an arena surrounded by depths. You need to use an updraft to reach him so Updraft Use is required. If your squad needs to restart you can jump down to save time and prevent armor damage.
He will aggro as soon as you land so don't start gliding before your squad is ready. However the timer only starts after someone attacks him. If you are the first to land and want to save few seconds don't attack him first.
There are 4 updrafts around the arena. You need to use them during the fight. They can only be used once so plan the order you are going to use them.
The phase 1 starts when someone attacks. He gets a Ghostly Aura which deals low damage every 3 to all players.
His basic melee attack chain has two attacks, Wicked Swipe and Spectral Impact. Usually he uses two Swipes and then Impact but be also prepared for just a one Swipe. Swipe deals only a moderate damage so it's not something you have to worry about it. Try to still stay behind Gorseval at all times to prevent unnecessary damage.
Try to learn the animation for Spectral Impact as soon as possible. The attack causes an AoE at the target and PBAoE at the Gorseval. It's very easy to get hit by both AoEs and take lots of damage. Additionally the attack knocksback for 1.5 seconds so it's always better to spend 0.75 seconds to dodge it.
After one rotation Gorseval teleports to the middle and starts doing his Ghastly Rampage. During the attack he has a 4500 unit defiance bar and an unremovable retaliation buff. The attack causes an AoE pattern which consists of multiple black rings centered on the middle. AoE explodes after few seconds dealing lots of damage. It can't be blocked or evaded so you need to move out of it.
You should break the defiance as fast as possible to end the retaliation. The attack itself isn't very dangerous because it takes a while before AoE appears on the melee range. Fast hitting characters will have a trouble with the retaliation.
Gorseval will be knocked down briefly after the defiance is broken. Once he gets up he will summon 4 spirits which can beor . After few melee attack chains he will start channeling World Eater.
During World Eater, Gorseval will be inactive so you can attack him freely. However at the same time a orange circle starts expanding from the middle. When it reaches the edge everyone in the arena will be instantly defeated after a few seconds. Additionally Gorseval consumes all spirits for a stacking 10% damage increase. You need to destroy "a wall", jump to an updraft and stay in the air until it happens. Keep in mind that the updraft disappears so you need to use another next time.
World Eater takes a long time to finish so you want to keep attacking Gorseval as long as you can. The best way to do this is pulling him towards the updraft right after the defiance gets broken. Once he starts channeling you can attack both him and the wall so you don't lose any damage. Also try to cleave spirits and focus them down if needed. You should try to kill them all but letting one live is acceptable.
Once World Eater ends he will do 1-2? attack chains, Ghastly Rampage, summoning, 2 attack chains and finally World Eater again. This time you must get him 66% health before World Eater ends. At 66% health the phase 2 starts which automatically ends the attack. Technically using an updraft is an option but you will run out of them if you do this.
The phase 2 starts with Gorseval being invulnerable. 4appear near each updraft and start slowly moving to Gorseval. Gorseval will restart World Eater if any Souls reach him which is really bad (unrecoverable?).
Souls are immune to control but you can use conditions like immobilize, chill and crippled to slow them down. The usual tactic is to have 3 players immobilizing 3 of the souls (1 for each) while remaining 7 players kill the last one. Once the soul is dead they move to the next one and so on.
Souls have a short aura which causes weakness so stay at range if you can. Also pay attention to other souls because people may need help, especially if they are getting attacked by previously summoned spirits. Gorseval becomes active when all souls have been killed so make sure everyone is near full health before you do that.
Gorseval behaves exactly same as in the phase 1. During the first World Eater you use an updraft and during the second you damage him to 33% health. The only difference is that traps calledappear all around the arena. Initially they don't do anything but over time they get a larger and larger circle around them. Walking to the circle causes 10 stacks of Spectral Darkness which equals 2000 damage per second along with other effects. You need to collect 2 golden droplets to get rid of it. Droplets appear on the arena when orbs are destroyed?
You need to have 1-2 ranged players to take care of Spectral Darkness. You don't have to destroy every single one of them. Instead the players should destroy them if they are nearby or are in a way to an updraft. Other players should help them if possible. For example melee players can destroy them as long as the circle is small.
The phase 3 starts exactly same as the phase 2. The only difference is that there might bein a way to a . Improvise as needed. If you can't attack the Soul and your squad can't destroy the Darkness, just go to another Soul. As before, ensure everyone is in good health before killing the last Soul.
Gorseval behaves almost same as in the phase 1. The only difference is that he will summon Ghostly Traps (delayed AoEs) at each player. If you get hit you will be encased in an egg which means a huge DPS loss because you won't be able to attack and people have to destroy the egg. You can get out by spamming the special action key or having people to destroy the egg. People getting egged is the biggest reason why squads fail killing Gorseval.
Ghostly traps can't be blocked or evaded so you have to move out. You can easily move out by just movement but dodging is recommended as it's slightly faster. The biggest threat are traps from other players. You can easily get surrounded if you don't watch out. This can be solved by either spreading out or stacking when you expect traps to spawn soon. Spreading is easier but results in a slight DPS loss because some players have to move out of melee range.
First traps appear after one melee chain. Second traps appear after Ghostly Rampage and summoning. Third traps appear after using an updraft.
If everything goes well you only need to use 3 updrafts. However if you have people defeated at the end you may need to use the last updraft. Using the updraft usually means that Gorseval enrages so don't use it unless you absolutely need it. Remember to communicate with your squad about the option you take.