The Ring of Sukhothai is a magical ring capable of transferring life force and youth from its victims to the wearer for as long as physical contact was maintained, even to the point where they could die of old age. It could also transfer the energies and powers of other magical objects to the user, such as those of the Manacle of Osiris, however such an occurrence could potentially create and spread powerful energy discharges in all directions.
When Anck-su-Namun escaped the Underworld, she woke up in the Temple of Sukhothai, where she took the ring and stole the youth of archaeologist Jane Sherman, who happened to be a friend and co-worker of Evelyn O'Connell. The O'Connells appeared soon after to investigate, where they found themselves face-to-face with Anck-Su-Namun for the second time.
She first stole some of Rick's youth, before severely draining Evelyn and Jonathan; when she attacked Alex, however, the Manacle's power prevented his youth from being drained and after several seconds knocked her back, but instead she slowly gained some of the Manacle's abilities with each touch. During one of their struggles, the others used mirrors to deflect some of the energy discharges back into Anck-Su-Namun, knocking her out for enough time to allow Alex to steal and destroy the ring, reversing all of the Ring's effects.