Start a mule character on a guest account. Get them up to 99 Eridium. Run through HBGH with your main character to the first Eridium drop-off/altar point. load mule character. spend THEIR Eridium. Exit mule w/o saving. Run to next 3 Eridium drop-off points. repeat loading, paying eridium, and exiting w/o saving with mule Fight Dexiduous with all initial Eridium, intact.