Maha Kola Sanniya is the great demon who heads the eighteen sanni yakku, the disease-demons of the lowland Sinhala exorcism cycle known as the Daha-ata Sanniya or Sanni Yakuma. According to the widely told origin myth, he was born of a queen of Vaishali who was wrongly executed for adultery; surviving in the womb and feeding on his dead mother's flesh, he grew into a demon and, to avenge her, fashioned eighteen disease-demons from leaf-bundles and poisons, loosing them upon his father's city. Each of the eighteen personifies a specific malady — blindness, lameness, deafness, fevers, vomiting, bilious and phlegmatic disorders, insanity and the rest — and in the Sanni Yakuma a masked dancer comes forward for each in turn so the exorcist may command the responsible demon to quit the patient's body. As chief he is also called Maru Sanniya, and his great composite mask gathers the eighteen lesser demon-faces about his own.