Hello
If you want to take into account all these factors, you need to think carefully and try to set up bosses. In what area does this or that boss appear, where do you place him so that he appears, will players be able to find a place where the NPC cannot pass in this area and what his ability or weapon will control it.
If you have given the bosses melee weapons, then you most likely need some short distances for this so that the boss is not on an open surface. Otherwise, it will be easy to shoot him from long distances while he is running to the goal. Or vice versa, if you give the boss a long-range weapon, such as a sniper rifle, then the terrain where he is located should correspond to him so that it is an open surface, and the boss is at a height so that it is more difficult to kill him. Let's say some kind of tower on the mountain and some garbage from below so that players can at least hide behind them to fight with him.
If you give the boss a shotgun, then this area must be something inside the building so that he can shoot at the target from a short distance and most effectively open up the possibilities of his weapon.
The best option is to create separate locations for each of the bosses and find the best weapons and abilities for him. If you use a procedural map, then you use monuments in Rust, this is not an ideal option, but at least something close to it.
Perhaps the boss has some kind of legend, make a location for it, give him the appropriate clothes, weapons with skins.
If you have a problem that players build houses and kill bosses from there, give the boss a rocket launcher, and he will then raid them.
If there is a problem with melee weapons, then update the NpcSpawn plugin, my last updates were aimed at improving the use of melee weapons by NPCs.
If you say that players use mountains, yes they will use it, you gave them this opportunity when you placed the boss near the mountain, because he will not be able to climb it. Players should not have such an opportunity, you need to calculate exactly what a player can do in the active boss zone, and exclude all options for using such controversial situations