I despise people that play Conan Exiles as if it was Minecraft. If they want to reclaim the whole server, just play solo and invite your friends to local game.
A few months ago, we came back to ‘our’ official server after a half-year-long hiatus. Of course, everything was gone, and we found that one of those clans had taken hold of the server. A couple huge/main bases, and a huge residence for each of them in several zones. They were also slowly walling every access to the whole brimstone basin, first occupying every tunnel and turning it into a bunker, then just building walls in more open areas. Needless to say, the server was pretty empty as a result. With the help of another clan (which ended switching servers anyway), we… uh… removed all their bases over the course of a week, which caused them to ragequit and leave the server, and decay did the rest.
Essentially, we’re the “Alpha” clan now. We mostly keep to ourselves; our base, though huge, is built in a relatively secluded place, and we build upwards if we ever need more space. Sure, you can get some lag if you come close to it because it’s really big, but since it’s not in a place where you’d stumble upon it unless you were searching for it on purpose, it’s not an issue that affects anyone. Also, aside for a couple slave wheels placed in strategic positions, we try to not build in other places. That’s because we actually want other people to come and prosper instead of living in a phantom server, and we know firsthand the despair of finding half the map reclaimed, and almost every single good cave taken too… all by the same clan.
In fact, we’ve nuked guys that came and started doing things like building around obelisks and lorestones, because a**holes aren’t allowed here. This is what people on top of the chain should do, instead of just becoming massive Richards. We’re not against people attacking each other (or even us, for the matter), we just enforce the rules that Funcom set, but without having to resort to slow bureaucracy.
TL;DR: Bid your time and blow them up; Minecraft players might have enough resources to rebuild everything, but seeing their work thoroughly destroyed will probably make them ragequit, especially if you convince them that you’re able to do it again. Alternatively, server 1083 is always open for people that want to prosper, as long as we’re able to “police” it.