Your main "progression" is making Lucia weaker. The game has a direct cause-and-effect system between your actions and her stats:
buff (which grants Sheer Force and Crit Damage) scales off her initial HP. You should aim for roughly 24,000 max HP to reach her buff ceiling. Skill Leveling : Prioritize her Special Attack fallen princess lucia guide top
While in Dream State, hitting enemies triggers aftershocks every 8 seconds, which can boost team damage by 10%. Your main "progression" is making Lucia weaker