You must stop King Moggle Mog XII and the Mogglesguard from threatening the Twelveswood.
How to Unlock
The Thornmarch (Hard) trial is unlocked by the level 50 Main Scenario Quest You Have Selected Regicide.
Changes to this Battle
This battle was changed significantly in patch 6.1. The moogles no longer need to be defeated in a specific order.
Phase 1
The battle begins with a sword-and-shield moogle named Whisperwall Kupdi Koop, who will sometimes cast Spinning Mogshield, a circle attack centered on Kupdi Koop.
After you defeat Kupdi Koop, a bow-and-arrow moogle named Woolywart Kupqu Kogi and an axe moogle named Ruffletuft Kupta Kapa will appear. The axe moogle will sometimes target a random player with 1000-kuponze Swipe, a cone attack. The bow-and-arrow moogle will sometimes cast Mograin of Darkness, which 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.
When you have defeated both of them, a healer moogle named Furryfoot Kupli Kipp and a harp moogle named Puksi Piko the Shaggysong will appear. The healer moogle will sometimes cast Pom Holy, which damages all players, and the harp moogle will sometimes target a random player with Moggleday Night Fever, a wide cone attack. If you get hit with this cone attack, you will be inflicted with Rhythmetic Fever, which temporarily prevents you from doing anything but dancing, while you receive damage over time.
After they are defeated, a dagger moogle named Pukna Pako the Tailturner and a black mage moogle named Pukla Puki the Pomburner will appear. The black mage moogle will sometimes cast Pom Meteor, which places four meteor circles in the area. Make sure that at least one player is standing in each of these circles before the moogle-head meteors fall onto them. Each meteor circle will glow more brightly when a player is standing in it. The dagger moogle will sometimes cast Moogle Thrust, which is a high-damage attack on the player highest in the enmity list.
After this, the moogles will dance, signaling the start of the second phase.
Phase 2
Good King Moggle Mog XII will appear and cast Memento Moogle, damaging all players.
He will then cast Good King's Decree, which will revive some of the defeated moogles. These moogles will use attacks that you saw in the first phase, as well as some new attacks. The revived moogles are untargetable, so just focus all attacks on the king.
The dagger moogle can cast Pom Bog, a large circle attack that leaves a large poison puddle in the area.
The healer moogle can cast Pom Stone III, which places a large circle attack marker in the center of the area, and a donut attack marker around the edge. This is followed a moment later by a donut attack that covers the safe area between the first circle and donut. Wait for the circle or outer donut to disappear, then move into the safe area where one of them was.
Throughout the battle, Moggle Mog XII will sometimes cast Mog Stone IV, which targets two random players with stack markers. The two marked players should not stand near each other. Unmarked players should stack together with one of the marked players to reduce the damage of the attack. Make sure that at least one unmarked player is standing in each marked player's stack marker.
The moogles will sometimes also cast Moogle-Go-Round, which places multiple very large circle attack markers in the area. Move into the last circle marker to appear, then when the neighboring circle disappears, move into the area where it was.
The king will sometimes cast Twin Pom Meteor, placing a dual stack marker on one of the tanks. The other tank should stack together with the marked tank. This is a high-damage attack, so all other players should avoid standing in the stack marker.
The king sometimes casts Mog Comet, which targets random players with a series of circle attacks that follow them. These player should move away from the circle attack markers and also stay away from other players to avoid placing the circle attack markers under them.
The king sometimes casts Mog Creation, targeting a random player with a line attack marker.
The king sometimes casts 1000-kuponze Charge, which is a high-damage attack on the player highest in the enmity list.
Completing the Quest
Defeating Moggle Mog XII will complete one of the quest objectives for the Main Scenario Quest You Have Selected Regicide.