From Zelda - Wiki on Neoseeker

Background

The Spirit Temple, where Link obtains the Spirit Medallion from the the Temple Sage Nabooru, is Link's final stop on his quest to collect the six Medallions - necessary items for defeating Ganon that house the power of the six Sages. Link must tackle this dungeon in two parts: One as a child, and the other as an adult. As a child, Link must venture into the temple and retrieve the Silver Gauntlets for Nabooru. As soon as Link takes the Silver Gauntlets from their chest, a brief scene occurs where Nabooru is captured by the evil sorceress sisters - Kotake and Koume (collectively Twinrova). Link returns to the temple as an adult - Silver Gauntlets in hand - and proceeds to exploring the rest of the temple.

Dungeon Boss

The boss of the Spirit Temple is none other than Twinrova, Kotake and Koume's powerful combined form. Link must use the Mirror Shield that he found in the Spirit Temple to reflect their attacks back at them. When Koume attacks with fire, Link sends it right back at Kotake. When Kotake attacks with ice, Links reflects her attack back at her sister Koume. When the sisters assume the form of Twinrova, Link must use the Mirror Shield to absorb three of their elemental attacks. After absorbing three attacks of the same element, Link can send a powerful elemental attack of his own back at them, by aiming the face of the shield at Twinrova.