>>32162
It has nothing to do with your build, you can visit the DLC area as soon as your reach Core City but I decided to do all quests in the main game first.
What I didn't know is there is a certain quest that locks you into the end game area (I don't want to spoil) and only lets you leave after you kill the final boss.
But I wanted to face him after having done anything else.
So my plan was
base game -> dlc -> final boss
But yeah now I know better and I won't go past this unannounced Point of No Return before having done literally everything else.