The Ritual of Tellann was performed by the Imass Bonecaster, Olar Ethil, transforming most of the Imass people into the T'lan Imass. It was "the binding of the Tellann Warren to each and every Imass. The ritual made them immortal [...] The life force of an entire people was bound in the name of a holy war destined to last for millennia." The purpose of the ritual was to make the T'lan Imass capable of exterminating the Jaghut people. Kilava Onass was the only Imass known to have escaped the ritual. The Imass also included their hunting partners, the ay in this ritual, creating the T'lan Ay.