3 suggestions. AI for Thralls, Buidling Hearth with blueprint, and alternativ dimension travel (server change)
Suggestion for AI for Thralls:
If you give a Thrall a pickaxe, it should go farming. Need a Thrall resource drop off point to then. If you dont arm it, it means run back home if you get attacked (and let the arches make a pinncusion of whatever). If you give em a meatcleaver, they hunt etc (and stock up the Thralls food storage) etc. Some Thralls may die, but that is a sacrifice what I am willing to take 
Makes the Thralls more useful and dynamic
Suggestion 2: Building blueprints (saves, even across servers)
Blueprint. House get a “hearth”. In this hearth is a blueprint and storage, so if building get damaged, the thralls fix it (based on what they have farmed, and given som AI). When you click on “blueprint” you sort of save the building (all the things connected by the same foundation… or 100 x 100 x 100 grid… whatever is easiest to program.). Thought that the blueprints follow the game, not the server, so they can go between servers and solo too. (sort of a backup of your work…)
Other dimensions.
A trippelstar monster might drop a ingredient for interdiensional travel of parallel worlds. (server change). The Hearth of house crosses servers. For example, you made a grand building in solo mode, but wish to teleport it to a PvP or PvE server, a special item dropped gives you the opportunity for this.
Transfer of house and Thralls might be instant, or Thralls build it up based on the materials in the hearth storage (they need AI for this), and based on blueprint. Hearth of building will be both blueprint and hold materials that cross servers. If you do changes in new dimension, and use blueprint, you save the changes for all servers. If hearth of building looses it health (your building gets destroyed in PvP mode, or PvE where you neightbours invite strong monsters to you place to take it down), The hearth escapes back to solo world with its content. So you still can take with you much of the stuff from you got in PvP and PvE back, even if building get destroyed when you are offline. Next server reset, and you back for round 2. This time with more archers and traps… ofc. many building spots are popular… but most people have probably many buildings too…so one spot should be free…
I can see some theatrics too… like your choosen deity (well, except Crom) clears the area if the Thralls are to build in total peace for a limiited time and to annonce you are here.
Also though about tiers… solo --> PvE --> PvP --> Grand PVP (only the strongest whos buidling survives a whole cycle of PvP) get to teleport to Grand Server. Special clothing for those
(been a bit inspired of the Minecrafts mods where the villagers actually go around building buildings on random places, so the NPC do a bit more than just look pretty and fight… so blueprint can work in solo mod too. Tamers Clan building something in the neighbourhood etc… Thought the same programming of villagers in Minecraft, they could actually make entire castles and towns around… based on a random bluerpint of a random player in the world so building fits the terrain… )