Dusk Diver 2

Story-related and cannot be missed.

Chapter Unlocks: New items in Tumaz Mart Secret Store. New max Orb Synthesis level & recipe: Clear Orb (level 4). (Required to create Rank 5 Orbs; see This Is...?! .)
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This trophy is for completing Chapter 10, "Elysium", which is another all-story Chapter; once again, there are no new side quests as they are still on pause. As mentioned in the trophy above, this is one of the rare times when a Chapter ends and a new one begins while you're still out in Youshanding. You do not return to the Tumaz Mart (or the Human Realm at all) in between Chapters. Instead, you're immediately thrown into the next part of the story quest.
 

At the end of the previous Chapter (Chapter 9; Salvage, Sally ), Ull picks you up after the boss fight. When this Chapter begins, he drops you off at a new area: the bottom half of Dragon Vein Lake (Hills). You will have to traverse the Hills to reach Fort Avalon.

There's nothing special in either location; no unique mechanic or challenge. Just keep moving forward and killing the robots and beasts as they spawn.

In Fort Avalon, once you reach the closed gates, Raven approaches you and knocks you all the way back down to the top-half of the Dragon Vein Lake.

BOSS FIGHT: RAVEN - PART 2
Once you're back in the Dragon Vein Lake (Hills), you'll have to face the first of this Chapter's two bosses: Raven. Once again, this is the same exact fight that you faced back in Chapter 6 (Masquerade Party ). There's really nothing new to mention here. Just fight her again until you win.

Once you beat Raven, you will automatically be taken back to Fort Avalon. Proceed through the area yet again. Once you reach the still-closed gate, you'll have to defend Boss as she hacks into 3 separate "Dragon Vein Interference Devices" (AKA the large shiny blue spheres that Hesperia claims is for clean energy). After that's over, when you proceed through the now-open gate, a little further in is your second (and thankfully final) boss of this Chapter: Vandak.

First though, you'll have a long cutscene wherein you learn a lot about what's really going on.

BOSS FIGHT: VANDAK
While Vandak is quick and agile, it seems his armor and health are somewhat weak as he takes a lot of damage (for a boss, at least). However, this is really more of a teaser, or a mini-boss fight, as once he reaches 60% health, the fight and the Chapter ends.