Hraesvelgr would have you complete a trial to test your resolve before making a decision.
How to Unlock
The Sohr Khai 4-player dungeon is unlocked by the level 60 Main Scenario Quest Winning Over the Wyrm.
Defeat Captain Mogsun to prevent him from tethering to the boss. Chieftain Moglin will periodically revive him, so be sure to kill Captain Mogsun again whenever he reappears.
You can prevent Chieftain Moglin from reviving moogles by knocking the moogles out of the purple puddles on the ground before Moglin can finish reviving them.
When a weapon floats in a random location in the area, stay away from it to avoid getting hit by its cross-shaped attack.
The Pomguard Pomfryer will cast a large Pom Flare attack, so you may wish to defeat it first.
Burning Bright is a lightning attack that hits all players in line with the boss. Players can move out of the way that the boss is facing to avoid this attack. If this attack hits a wall, the wall will be destroyed and replaced by an electrified floor. Standing on an electrified floor will inflict a temporary Electrocution status. Players can minimize the number of walls that get destroyed by staying in the center or staying between the boss and the outer edge of the area.
When Poqhiraj flies up into the air, a proximity marker will appear on one side of the area. Go to the other side of the area to reduce the damage that you take from Touchdown.
After Poqhiraj lands, it will cast Gallop, marking the ground with a spreading line marker. Go as far away from the center of this line as you can, up against a wall. If there is no wall, you will be knocked onto the electrified floor by this attack. If you are too close to the center, you will be knocked into the sky and get a Vulnerability Up status.
Poqhiraj will target random players with Cloud Call, which makes a Dark Cloud appear above their heads. The Dark Cloud will repeatedly cast Lightning Bolt, a circle attack, which inflicts a Vulnerability Up status with each hit. Players can drop these in the middle of the area near a wall or electrified floor, to prevent placing a Dark Cloud near a far edge where players may have to dodge it when they run away from the proximity marker.
Wyrmclaw is a high-damage attack on the player highest in the enmity list.
When the boss casts Hallowed Wings, one of his wings will glow. There will be a line attack that hits the side of the area with the glowing wing, so don't be on the same side as the glowing wing.
Holy Storm damages all players.
Hallowed Dive is a line attack through the middle of the area, followed by a set of circle attacks that move in a line along the sides. First, go to one of the sides to avoid the line attack, then move into the area where the line attack went off, to be safe from the circle attacks.
Akh Morn targets a random player with a stack marker. Unmarked players should stack together with the marked player to reduce the damage of the attack. This is a repeated attack, so stay stacked together until the attack stops.
Holy Breath marks all players with circle attack markers that follow them. Players should spread apart from each other to avoid overlapping each other with their circles.
Diamond Storm damages all players and freezes the ground. While the ground is frozen, you will slide a short distance whenever you move, so be careful to avoid sliding into attack markers.
Frigid Dive is a line attack through the middle of the area while the ground is frozen. Move carefully to slide out of the attack marker.
After Frigid Dive, there will be a series of circle attack markers. Move carefully to slide out of the circle markers and try to avoid sliding into other circles.
Completing the Quest
Defeating the boss will complete one of the quest objectives for the Main Scenario Quest Winning Over the Wyrm.