General Umbriss works on a 25 seconds loop. The main components as a healer are the tank buster Skullsplitter followed 7 seconds later by Commanding Roar. This is a fight where your main concern might be your tank. Skullsplitter leaves a heavy DOT, and the Roar will trigger the lines mechanic, forcing them to move. This can really hinder their capacity to maintain their defensives. Keep an eye on them, and be ready to help out!

Forgemaster Throngus rotates between three weapons every 20 seconds, each comes with a specific mechanic. The act of forging is what creates the AOE damage with Blistering Heat. The only real other source of damage is the Molten Spark when he wields the sword. Make sure the targets quickly before the next forging!

You will fight Drahga alone at first, until you get them to very low health, and they will mount Valiona, until Valiona gets to mid health, signaling the end of the fight.

Dragha will spam cast Shadowflame Bolt which should generally be interrupted, there is nothing else to interrupt. Otherwise they will cast Curse of Entropy which is simply a healing absorb on a 25 seconds cooldown (and a snare, think anti-snare tools to remove it). This is not dangerous in itself during P1.

P2 however adds new sources of damage. Twilight Buffet is on a 35 seconds cooldown, and you want to make sure everybody is healthy enough ahead of it. If the boss is well handled, this should be about it, but things can quickly get messy creating a lot of Twilight Wind damage. Note that Curse of Entropy will only be cast every 35 seconds, shortly after each Twilight Buffet. This has the effect of keeping people at lower health a little longer if you were not quick enough to heal the group.

Erudax presents a fair healing challenge, that is made really complicated by the positioning puzzles their mechanics present to your group.

The boss works on a 50 seconds loop. They will open with Void Surge, your standard Burst AOE, before they make everybody move to the "eye of the storm" Shadow Gale. 25 seconds after the initial Surge, they will cast Abyssal Corruption on three targets creating high spot damage. Then they will summon adds (Void Infusion), blast the tank (Crush) and repeat the sequence.

The mechanics are messy and death can happen very fast, thanks to the not overtuned 4 seconds DG stun hitting a tentacle will create. What adds to the healing challenge however is that the adds will apply a stack of Shadow Wound on the whole group when they die. This is a mechanic that is very reminiscent of the last corridor of Throne of the Tides (Dragonflight version). The ideal timing to kill the add is right as Void Surge ends so that it will disappear before Abyssal Corruption, and this is of course easier said than done.