After the events unfold on the Steps of Faith, you prepare for a confrontation.
How to Unlock
The Final Steps of Faith 8-player trial is unlocked by the level 60 Main Scenario Quest An End to the Song.
The main tank should turn Nidhogg away from the party.
The Scarlet Whisper is a cone attack at the player highest on the enmity list.
Deafening Bellow damages all players.
Horrid Roar is a circle attack that appears under several players. You can dodge this before the circle appears by looking for a bright slash that appears beneath you just before the circle appears.
Hot Wing is an attack that hits all but the line from Nidhogg's head and tail.
Nidhogg will sometimes fly up and go to the edge of the area. Don't be in front of Nidhogg because he will soon use Cauterize, marking a large part of the area with a line of fire in front of him. Stay out of this line to avoid the attack.
At 75% health, Nidhogg flies to the edge and summons a Shadow Dragon, Shadow Falak, and Shadow Brobinyak.
One tank should attack the Shadow Falak and get to the top of its enmity list, and the other tank should do the same on the Shadow Brobinyak. The Shadow Dragon attacks random players regardless of enmity.
The Shadow Dragon attacks random players with Ripper Claw, which inflicts a Damage Down status. Players can avoid Ripper Claw by watching for when the dragon pulls back its arm, and getting out from in front of it before its attack.
The Shadow Falak attacks with Electric Predation, a cone attack. The Shadow Brobinyak attacks with The Serpent's Apple.
After you defeat the three enemies (or if you take too long), Nidhogg hits everyone with Mortal Chorus, which knocks back all players, then changes his form. After the boss's transformation, he hits everyone with Final Chorus, which deals a large amount of damage to all players.
In this form, Nidhogg periodically attacks with high-damage attacks Ala Morn and Drachenlance.
He will sometimes cast Geirskogul, a line attack that targets a random player.
He will sometimes target players with High Jump, a large circle attack that leaves a temporary puddle. Players targeted with this circle should go to an edge of the area to drop the puddle out of the way. This attack may also place a proximity marker for an attack called Super Jump. Players need to move away from the proximity marker to reduce damage from Super Jump. At the same time, there will be multiple Geirskogul line attacks to dodge.
Around 25%, Nidhogg hits everyone with Bloodrage and changes his form.
At this point, Nidhogg will repeat some of his previous attacks, with the addition of some new ones.
When Nidhogg casts Hot Wing which hits everything but the line from his head to his tail, he follows it with Hot Tail, which hits in a line from his head to his tail.
Nidhogg will sometimes spawn fireballs around himself. These will eventually explode in cross-shaped attacks going north-south and east-west. Be sure to stand diagonally to these fireballs to avoid the attack.
When Nidhogg stands up on his hind legs, a player will be marked with a stack marker, and all other players need to stack together with the marked player to share the damage from Akh Morn. After it hits, it will hit several more times, following the marked player (or hitting random players if the marked player dies), so it is best if all players stay still to continue sharing the damage until the attack subsides.
Completing the Quest
Defeating the boss will complete one of the quest objectives for the Main Scenario Quest The Final Steps of Faith. After you exit the area, there will be a cutscene. This one is important, so it is recommended to watch it either now or via the Unending Journey in an inn room.