After your battle with Zenos in Ala Mhigo, you ascend to the Royal Menagerie where you face another battle.
How to Unlock
The Royal Menagerie 8-player trial is unlocked by the level 70 Main Scenario Quest Stormblood.
The Corrupted Aether gauge refills throughout the battle, so keep an eye on it to be prepared to deal with the attacks from it.
Tidal Wave creates a water spout next to a random side of the area. The water spout will knock players away from it, so stand near the water spout to avoid being knocked off of the edge.
The water puddles that appear around the area do not do damage. They will be used in later attacks.
Hypernova marks a player with a stack marker. The other players should stack together with the marked player to reduce the damage.
Akh Morn is a multi-hit attack on the two players who are highest on the enmity list. These players should stand together to reduce the damage until the attack stops.
Spikecycles are two large line attack markers that alternate their positions. Stay out of the path of these line attacks and be prepared to move away from the subsequent line attacks.
Ice Storm damages all players.
Earth Breath marks two players, who will both targeted with cone attack markers originating from the boss. The attacks are not immediate; there is time to run away from the cone attack markers after they appear. For this reason, both players can go to a corner together to minimize the area that is covered by the cone attacks, then run to safety before the attacks hit.
When the Corrupted Aether gauge fills, the boss will either cast Hellfire or Judgement Bolt. If he is casting Hellfire, stand in a puddle to reduce the damage. If he is casting Judgement Bolt, stay away from the puddles to reduce damage.
Proximity attack markers will appear at three of the four corners of the area. Go to the safe corner where there is not a proximity marker.
After the proximity attacks hit, defeat the enemies that appear, and keep your distance from additional proximity attack markers that appear.
After the enemies are defeated, the boss will use Protostar, a high-damage attack on all players.
After this attack, all players will be chained. When the Active Time Maneuver begins, you can quickly type randomly on the keyboard or quickly press random buttons on the controller to fill the gauge and avoid death.
Afterward, there will be a very large line attack across the area. Quickly go to one of the two safe corners.
Tail Slap will mark part of the area with a line attack marker. Don't stand on this area, which will damage any blue tiles that it hits. Damaged blue tiles will be destroyed if hit a second time with Tail Slap. The center tile cannot be destroyed by this attack.
After Tail Slap, attack the boss's tail until it disappears, then resume attacks on Shinryu.
Burning Chains will mark two players with chain markers over their heads. These players must run away from each other until they break the chain between them.
Levin Bolt marks players with purple markers over their heads. These players should move away from others to avoid hitting them with this attack.
Dragonfist places a circle attack marker in the center of the area. Move out of the circle marker to avoid the attack.
Diamond Dust is an attack that requires all players to stop moving and attacking as soon as the cast bar fills. Be sure to stop your auto-attack by putting your weapon away (go to the official site's Basic Controls page and search for "Draw/Sheathe Weapon/Dismount" if you do not know how to do this), and don't move or use any actions until after this attack hits.
Earthen Fury damages all players.
Aerial Blast places a wind column in the center of the area that will repeatedly knock players away from it. Keep moving toward the center to avoid being knocked off of the edge.
Completing the Quest
Defeating the boss will complete one of the quest objectives for the Main Scenario Quest The Royal Menagerie. 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. Be sure to watch the post-credits scenes as well.