Okay, so this might sound weird, but what do I do after I clear the Dungeon of the Forsaken?
I guess I might've just not read closely enough, but no new areas have been opened up, and I don't know where else to go to continue :P
Thank you!

After you cleared the forsaken dungeon/Umbra forest, the next region that should open up is Astryl's vale.

You can only enter the different zones in that region if you're not currently in any zone though. So if you're in the festival zone, you have to exit from the festival zone (resetting all items and boss spawn times) to enter Astryl's vale. Likewise, once you get into any zone in Astryl's vale, to go to another zone within Astryl's vale or to go to the festival zone, you'll have to exit from the current zone you're in, losing all progress and resetting your position in the zone.

It's a bit confusing cause the third region functions on a different battling system than the first two. =P

Ah, I see. Every time I click on it, it just takes me to the winter festival zone, so I was confused.
But thanks for clearing it up!