You have to run to the boss first, the only obstacle in your way is your own jumping puzzle skill and the Irukandji, Jade Shards. The way to the boss is not really challenging as it can be ran through fast. If you happen to be in combat, jumping through will be a little bit harder but nothing extraordinary. Use Stealth to skip the mobs easily. Before doing the final jump onto the boss platform next to the Mistlock Singularity, make sure to have Swiftness so you don't fall to your death because there will be Agony applied to you mid-air.
Before you approach the boss, stack Might and kill the two Jade Tentacles, then the Irukandji. The Jade Tentacles have two skill, a huge spin AoE (so make sure to dodge it the right time) and after the spin, a stomping attack that can be side-stepped or dodged. Note that the tentacles can be CC'd like Stun or Daze.
After killing the Jade Tentacles new ones appear and the Jade Maw starts tagging players with a red skull and Jade Colossi starts spawning. The red skull is an indicator of an insta-downing skill which happens after the skull disappears from above the player. The skull can be dodged when the red skull disappears but mainly you want to pick up the Reflecting Crystals spawned by the Jade Colossi and the Jade Tentacles and throw them into the Jade Maw's Eye, this is the only way it can be damaged as normal skills won't damage him at all.
DO NOT kill all Jade Tentacles at once but move as a group from tentacle to tentacle as every tentacle cost the Jade Maw a small amount of HP, which however does not stack, if you kill them at the same time.
The Jade Colossi spawn with a reflecting aura that can be removed using non-projectile based CC skills such as Stun or Daze. The Jade Colossi has 3 skills, a far reaching skill that applies Crippled, an AoE Knockdown and a reflecting aura that looks like Elementalist's Magnetic Aura, the Jade Colossus mostly activates this aura after it got it's reflect stripped.
Constantly pick up Reflecting Crystal if you have the red skull above your head and keep doing it until the Jade Maw is at 5-8% HP, then he does the red skull on all 5 players in the party. All pick up a Reflecting Crystal and then you kill the Jade Maw. Congratulations, you finished the fractal.