I assume overworld means stuff in the open world in general like hunts and fates and whatnot if so then wouldnt the overworld primal summons be like hunts where anyone can just attack them?

I was thinking more inside dungeons type of raids where say the fc leader enters then only people from the same free company can enter also.

And the idea of randomized raids sounds cool this could go hand in hand with fc raids so every time a fc enters they have no idea what to expect in each raid keeps each one sort new.