I still think probably the most jarring thing about transitioning from Anemos to Pagos is simply the sound aggro. Anemos didn't make it much of an ordeal, and everyone gets into Pagos thinking they can just outrun the dragons or whatever else. Yeah, sure, map design and mob placement are still pretty terrible, but, personally, still found it bearable as long as I knew what I had to walk around.

What always surprises me is going off to rez someone fresh that got chomped by a dragon, and I'll explicitly say something like, "Sound aggro, walk, don't run." And they're always very surprised about this. Like. The dragons are sleeping. Of course you have to walk. That should be obvious. Yeah, many of the other sound enemies might not be, but the dragons should at least teach you that there are different aggro types to be aware of.

But, maybe it's just different for me. I recognized sound/sight aggro long before Eureka. One of the best examples I can think of is in Qarn, where you can literally skip the trash in the entire caves section just by walking. Both the bugs and the ghosts will only aggro by sound.