For the big encounter my players would have with the BBEG, I decided to have a whole underground dungeon. The first floor was a randomly generated dungeon I got online, nothing exciting there, but then descending into a hole, they’d come about some caverns (in the south portion of this map) and then discover old ruins, the BBEG channeling something in a ritual, which they tried to chase after, like I hoped, and then she escaped into the balcony, when the players ran towards the balcony, they saw the BBEG flying off into an underground city. I completely stole off this picture from the internets, I apologize for the artist of this, but alas, I don’t know who they are. :(
The good part though, is that my players reacted how I hoped after they reached the balconies! That kinda reveal ain’t easy to hold on to, but it paid off in the end!