An Evening of Diablerie takes place on an island in the Viennese Danube on the winter solstice, celebrating the longest hours of darkness when the Sun is reborn. Based on Austria’s folk history, this project weaves a narrative of mythology, theatricality and celebration into a building (nightclub, theatre and ritual pavilion) which bleeds in its symbolic transformation of character. The project draws on the folktale of Krampus, the Teutonic mythical creature that wards off Austria’s winter spirits. It interrogates and reconstructs this myth into a fairytale about Kralle who is Krampus reborn as a supernatural enchantress. The building sits on, is constructed from and inhabited by the Danube. The river's sediment and algae are used to construct Kralle as a breathing building with a circulatory system of algae, whilst its flow is manipulated in order to transform her into an enchantress. In order to perform the tale, liquid algae's colour is organically manipulated and its movement controlled. At the end of the ceremony, the algae discharges back into the Danube’s side channel, guiding visitors out of Kralle's body and creating a polychromatic spectacle at twilight before dawn.