A girl in the series, Mizuki got transformed into a statue as a result of a spell card. She later eventually reverted.
Onmyō Taisenki anime is related to the story regarding summoned monsters known as Shikigami and the battling of the monster's owners. The anime does have a reference of the Taoist element theories which applied on the cards used within the series.
In this episode, a battle between Yuuma and Ogami ensues which a spell card is used by Ogami on Mizuki, rendering her immobile and eventually petrifies as Ogami didn't want her to involve in the battle. Later on, she reverted back.
Watch online: GogoAnime