Vellayani Devi Temple, near the picturesque Vellayani lake, is a highly revered shrine whose origin dates back to 850 odd years. The temple has a huge idol locally known as Thirumudi' which is four and half feet in height and in breadth. The idol stands for Bhadrakali the daughter of Lord Shiva. Pure gold and precious stones adorned the front portion of the huge idol.

The shrine played major part in the social reformation of Kerala as it had let all communities to enter and worship the chief deity. The mega festival usually lasting more than 50 days itself is unique while considering the other festivals in India. Wide ranges of customs go with the festivals. Many of the customs are exclusively performed by certain classes of people. These observances and customs not seen or hardly practiced anywhere. People of all communities participating with much pomp and splendor and stands for unity.

Karadikottu' is the maiden custom related with the festival performed with a special drum. The performer is locally known as Panan'.

Kalamkaval' is a famous customs practiced at the temple premises and nearby placed during festival. It is believed that the Goddess Bhadrakali had searched her enemy Darukan' all directions before putting him to death. Devotees commemorate this legend by seeing this unique Kalamkaval. In Kalamkaval, the chief priest, not a Brahmin, carry the main idol on top of his head and performed until he become unconscious. It is believed that the performer get enough power to carry the huge idol by the blessings of Amma.

Uchabali' is another custom performed at midnight. About sixty four gestures like in Kadhakali' using for the performance. Mathsyam, sampannam, chathurasramam, sarppamudra, and jyothimudra are some of these gestures. Virgin girls are usually prohibited from watching Uchabali'. A beautiful crown built of coconut palm is fixed at the spot of Uchabali.

The festival, Kaliyoottu, ended with a grand procession knows as Arattu. During Arattu' the idol is cleaned using water collected from 101 pots. A little girl below aged ten years of aged performing the function with all its glory.