group finding a bunch of information about the Correan group "the Underwardens" who were tasked with the defense of the tunnels and care for the living planet (all of them are dead now, but the group looted their cache, so once I figure out what, there'll be new magic items)
In the ruins, the party utterly destroyed a clutch of beholder zombies.
Nick managing to clear the ruins of the cursed spirits trapped there, and the party deciding this might be a good place to use as a base.the group found a map of the tunnel lines across Vallene, too
The group throughly explored Giham, which is where the tunnel stopped (collapse, and Striboch was there). But there are likely other ruins or Correan cities/facilities at other points on the line. Almost certainly at the spots mentioned by that first Correan facility you checked out.
the ruins are far in the north, so emerging from them, the group finds themselves in a frozen wasteland. In the nearby town of Agvar, they make nice with the mayor, talk to the wise woman (who turns out to be an elf, living here since she fled the humans slaughtering her kind during the Godsblood wars), and discover that some people in town have a bit of Correan blood in them.
found this crazy huge storm just churning, somehow restrained to a small area.
Somon concludes it's a frost giant storm.
Agvar sometimes gets raided by frost giants
There's a small group outside the storm. Living in the forests, taking what they need to survive.
Fallen so far from their rightful place.
The group was joking that the ruins would be the foothold for your frost giant empire.And yeah, the tunnels run to every continent.