Xena: Warrior Princess Season 6 Episode 8

After Xena tells the tale of how Grendel was created, when the valkeryie Grunhilda put on the Rheingold ring, she, Gabrielle, and two Northern warriors kill the creature, only to learn it wasn't the one they though but her child instead. It's mother, Grunhilda, has the power of the ring and is bent on destroying Xena and anyone who gets in her way.