Getting Started in Rubinite

Standing closer to a boss fills the Focus gauge faster than fighting from range, so don't be afraid to get in close.
You can't swap Talismans mid-fight, but quitting to the hub (not dying) resets the boss to phase 1 while keeping your Talisman change — use this if your loadout isn't working for a later phase.
Blood Dust survives even when you lose — reaching half health on a boss still dumps resources into your inventory, so no attempt is wasted.
Defensive Talismans (like damage reduction shields) tend to outperform raw offense for learning players before tackling harder bosses like Guardian Faye.