In the center of Giran, speaking with NPC Fyrensia will allow you to enter the solo instance zone for epic bosses. However, certain conditions must be met, including the number of rebirths.
This is the primary way to obtain Gold Dust. The stronger the boss, the more Gold Dust you can acquire.
Instance zones reset every Monday, Wednesday, and Friday.
The main difference from epic bosses in the open world is that the chance to drop epic jewelry has been reduced to 15%, and the loot drop has been modified, with a small chance for CA progression.
The most important drop, aside from epic jewelry, is Gold Dust, which can be used to purchase various items, enhance accessories, and visualize your equipment.