I love the game, but: I don't really get why Hexia is so overtuned. I've had runs where I just quit if he shows up on floor 20 rather than the dragon because I know my party won't be able to take him.
Sure the dragon does a lot of damage but aside from the occasional poison it's just raw damage. In comparison, Hexia does slightly less damage with attacks but throws around pain, petrify, counter damage, counter damage on his adds, counter damage when you cast spells, and adds with 12 base hp.
Some of these are hard counters to specific parties and you have no idea what final boss you're going to get.