She wants you to slaughter her sister Kali, a General in the Black Ring who killed their own father, and retrieve Myrthos, a powerful one-handed sword that he forged. Travel to Kali's Flying Fortress in the Orobas Fjords using your dragon form, and confront her in the fortress' headquarters on the southern-most platform. After killing her and obtaining the sword, return to Hermosa at the Battle Tower.