Ethereal Medallions are a boss-earned currency in Reborn that grant early access to chosen gear without deep quest or specific area progression. (looking at you, DMGS)
Cost scales by power, ranging from 1 medallion for common items to 50 medallions for late-game gear.
Boss drops:
To exchange Ethereal Medallions, visit the Ethereal Maiden at the Roundtable Hold. She can be found beyond the gate at the end of the great hallway.