When I was playing my second run of EA, I just figure out that the different portals should potentially allow you to return to one location of the chapter 1.
If I refer to my experience with DOS 2, leaving the chapter is closing definitly the access to the map from this chapter.
Again a story a boat
But anyway, from a functional point of view, getting access to a small part of map from chapter 1 should be possible through the portal. And we have already in this area some nice locations for a stronghold to be established.
What i call stronghold is like a permanent base which can established by the PCs, which can be improved with new areas, features and potentially hosting some NPC for specific tasks (like guards, merchants, artisans, refugee, animals , etc).
Getting a stronghold is a major quest and can trigger a bunch of small quests according to the location. Here are some examples :
Rebuilding the Waukyne Rest.
=> Recruit staff, guards, specialist merchant (cooker), musicians.
=> Small quests can be established related to travellers.
=> Inn can be also randomly attacked by raiders.
=> Once rebuild, you gain money from the inn.
=> You have to provide or invest on some stuff for the inn to work efficiently.
Rebuilding the ruined village.
=> Recruit new citizens including tieflings from camp.
=> Small quests can be established related to travellers.
=> Village can be also randomly attacked by raiders.
=> Quest to move the portal stone outside of the village (too dangerous inside)
Cavern in Druid camp.
=> The cavern used by Zevellor can be allowed to be used by the party.
Selune Temple.
Can be transformed into a temple for another deity or be used to do what you want in fact 😊.
=> Recruit staff, guards, trainers, merchants
=> Small quests can be established related to travellers.
=> Temple can be also attacked by raiders.
=> Guards can securize weak points
=> Old goblin camp can be transformed as optional village.
Arcanic tower (since it appears it is not occupied)
=> Hire masons to repair the floors.
=> Bernard could be a perfect steward for this place. (Bernard is a reference to Westworld, doesn't it ?)
=> Arcanic tower could not reveal all of these secrets. It seems it can move. Is it possible to move it outside the UnderDark ?
Abandonned village in Underdark
(place is incredibly beautiful but a poor choice for a lair since not easy defendable).
=> An house can be offered by the gnomes after delivering them.
=> Gnomes can also prepare a cavern near the village for you that you can customize. Including the shining stones or luminous mushrooms.
=> Recruit staff, guards, merchants (especially gnomes and Seldarin drows)
=> Improve defense of the village
=> Village and stronghold can be attacked by different packs and creatures
Gnoll cavern.
=> Can be transformed into a cozy underground place.
Owlbear cavern.
Can be transformed into a cozy underground place.
Selune 's outpost in Underdark
Can be transformed into a cozy underground place.
Zhentarim cavern
(if you become a Zhentarim friend or not ; in this case, Zhentarims can send increasing forces to take back the place)
Lof of work to do that for sure but what do you think about this idea ?