What is a leak? Bali's black magic and night-witches explained

Bali's night-witches of the Calon Arang legend, the flying head, the witch-queen Rangda, and the healers and offerings raised to hold them in balance.

9 min read · Published 28 August 2026

First, the answer

A leak, also spelled leyak, is a practitioner of black magic in Balinese folk belief. One who has learned ilmu leak, sometimes called penestian, the dark counterpart to Bali's protective magic. In the most dramatic tellings a leak by night leaves its body and becomes a flying, disembodied head trailing its entrails, said to feed on foetuses or corpses. Leak are connected to the witch-queen Rangda and to the Calon Arang legend, and are countered by a balian, a Balinese healer, with offerings and the keris. Bali frames good and evil as rwa bhineda, a balance instead of a simple war, and accounts of leak vary widely.

What a leak is

A leak (spelled *leyak* in Balinese) is, in the folk belief of Bali, a practitioner of black magic: a person who has studied and mastered ilmu leak, the knowledge of the dark arts, sometimes called penestian. This stands as the shadow counterpart to Bali's protective, benevolent magic; the same broad craft of ritual power can be turned, in the telling, either to guard or to harm.

It counts to be clear at the outset that a leak is understood as a human practitioner, not simply a monster. Someone who has sought this knowledge and can wield it. That framing runs through Balinese belief, where the line between the seen and unseen worlds is close, and where power is neither wholly good nor wholly evil but depends on the hand that holds it.

The flying head

The image that has travelled furthest is the most dramatic one. In the vivid tellings, a leak by night is able to leave its body: the head detaching and taking flight, trailing the entrails and organs beneath it, glowing or fanged, roaming in the dark. In this form the leak is said to seek out the vulnerable: to feed on a foetus in the womb, or on the blood and flesh of the newly dead, haunting graveyards and the houses of the pregnant and the sick.

This is the leak of Balinese horror imagery, and it's real as folklore, but it deserves flagging frankly that not every account runs to the flying head. In other tellings a leak is simply a person of harmful magic who can take animal or monstrous shapes, cause illness, or work misfortune, without the disembodied flight at all. Accounts vary, and the most lurid version is one strand among several, not the whole belief.

Rangda and Barong are the point: balance, not victory. I'd stop reading Bali's magic as a war.

Rangda and the Calon Arang legend

The leak don't stand alone. In Balinese lore they're ruled by Rangda, the fearsome witch-queen, a towering figure with wild hair, bulging eyes and a long tongue, queen of the leak and mistress of dark magic. Rangda is one of the most recognisable images in Balinese art and performance, and she isn't a simple villain: she embodies a real and necessary force in the cosmos.

Her story is bound to the Calon Arang, a legend cherished and retold across Bali of a powerful widow-witch whose sorcery brings plague and ruin until she is confronted. From this legend comes the famous Barong and Rangda dance, in which Rangda faces the Barong: a benevolent lion-like guardian spirit. Crucially, the dance does not end in a clean victory. The two forces clash and neither is destroyed; the performance closes with the world's balance restored rather than with evil wiped out. That's the Balinese point exactly.

How leak are countered

Against the leak stands Bali's protective tradition, and it works through people, offerings and objects rather than through any promise of final destruction.

The balian. The balian is the Balinese traditional healer and ritual specialist: the counterweight to the leak. A balian is consulted to diagnose whether misfortune or illness is the work of dark magic, and to shield, treat and turn it away.
Offerings. Daily banten and canang (the small woven trays of flowers, rice and incense laid out across Bali) are given to keep the unseen world in good relation and the malign forces appeased and held at bay.
The keris. The keris, the sacred wavy-bladed dagger, brings deep spiritual power in Balinese belief and appears as a protective force in the Barong tradition against Rangda and the leak.
Protective magic. The benevolent side of ilmu (the guarding craft that mirrors penestian) is drawn on to defend a household or a person, magic set against magic.

The Calon Arang story, told

The legend is set in eleventh-century East Java, in the reign of King Airlangga. Calon Arang is a widow of the village of Girah, a mistress of black magic, whose daughter Ratna Manggali is beautiful and cannot find a husband, because every family fears the mother. In her rage Calon Arang goes with her disciples to the graveyard, calls on the goddess Durga, and sends plague across the kingdom.

The king sends his sage, Mpu Bharada, who cannot defeat her by force. Instead his disciple Bahula marries Ratna Manggali, wins her trust, and borrows the widow's book of magic, which Mpu Bharada reads and turns against her. In some tellings she is destroyed; in others she is released and purified, and the plague lifts. Bali took the story from Java and made it its own, and the Rangda mask is Calon Arang in her graveyard form.

What you are watching in a Barong dance

The performance most visitors see is a cut-down version of a temple rite. The Barong enters first, a shaggy lion-like creature worked by two dancers, playful and protective. Rangda enters from the graveyard side with her long nails and lolling tongue. The two confront each other, and a group of men with keris blades rush to attack Rangda on the Barong's behalf.

Rangda's magic turns their blades on themselves. In the temple version the men enter trance and press the keris into their own chests without wounding themselves, a state called ngurek, and a pemangku priest brings them out of it with holy water afterwards. In the tourist version at Batubulan and elsewhere this is choreographed. Neither side wins. That is the point of the piece and the reason it ends with the priest and not with a death.

Two kinds of balian

The healer who stands against the leak is not one figure. A balian usada has learned from the lontar texts, the palm-leaf manuscripts of Balinese medicine and ritual, and works with herbs, massage and formulae. A balian taksu works by trance, receiving guidance from a spirit or ancestor, and is consulted to find the cause of an illness that has no visible one, which is where a diagnosis of leak may arrive.

Many Balinese consult both, and a hospital besides. A visit to the balian to ask why, and to the clinic to ask what, is not a contradiction in Bali. It is the ordinary way of covering the seen and the unseen at once.

The belief today

Certain villages carry a reputation, usually unfairly, and locals will not name them to outsiders. The reputation is the same social weight that santet carries in Java, discussed in what santet is.
Nightly protection is ordinary. A small offering at the gate, a length of white and black checked cloth, the poleng, on a shrine or tree. These are for balance, not fear.
Illness with no clear cause still raises the question, and the balian taksu still answers it. Where the answer names a person, the same harm follows as anywhere else, so balian are careful about naming.
The tourist economy has put the leak on T-shirts. Balinese people are generally relaxed about this. The dance was always public, and Rangda was always meant to be seen.

Rwa bhineda: balance, not a simple war

To understand the leak you have to understand how Bali frames good and evil, and it isn't as a war one side is meant to win. The principle is rwa bhineda: the two opposites, the complementary duality that holds the world together. Light needs dark, order needs chaos, the Barong needs Rangda; each defines and balances the other, and the aim of ritual is to keep them in equilibrium, not to abolish one.

This is why the leak, for all its horror, isn't simply a thing to be exterminated in the telling. It's one pole of a living balance, and the offerings laid out each morning are less a battle than a tending, a keeping of good terms with every force in a crowded unseen world. It's a subtler and, in its way, more mature cosmology than a straight contest of hero and monster, and it is central to how Balinese belief holds together.

The register to keep is respect. The people who lay the canang each dawn and who tell the Calon Arang are not credulous; they carry one of the world's richest living ritual cultures, and the leak is one thread of it.

What is a leak in Balinese belief?

A leak, also spelled leyak, is a practitioner of black magic in Balinese folk belief. A human who has mastered ilmu leak, or penestian, the dark counterpart to Bali's protective magic. In the most dramatic tellings a leak can leave its body by night as a flying head trailing its entrails, though accounts of leak vary widely.

Is a leak really a flying head?

That's the most vivid strand of the folklore, in which a leak by night detaches its head, trailing organs, to feed on foetuses or corpses. But not every account runs that far; in other tellings a leak is simply a person of harmful magic who can take monstrous or animal shapes and cause illness. It is one version among several instead of the whole belief.

Who is Rangda?

Rangda is the fearsome witch-queen of Balinese lore, queen of the leak and mistress of dark magic, recognisable by her wild hair, bulging eyes and long tongue. She is bound to the Calon Arang legend and to the Barong and Rangda dance, where she embodies a necessary force in the cosmos rather than a simple villain.

How do Balinese people counter a leak?

Against a leak stands the balian, the Balinese healer, who diagnoses and turns away dark magic. Protection also works through daily offerings called banten and canang, through the sacred keris dagger, and through the benevolent side of ritual magic. The aim is to hold the harmful force at bay, not to destroy it outright.

What is rwa bhineda?

Rwa bhineda is the Balinese principle of complementary duality, two opposites, such as good and evil or order and chaos, that need and balance each other. It's why the Barong and Rangda dance ends in restored balance instead of a clean victory, and why the leak is treated as one pole of a living equilibrium instead of a thing simply to be wiped out.

What is the Calon Arang legend?

An eleventh-century Javanese story of a widow and sorceress whose daughter cannot marry because families fear the mother. She sends plague on the kingdom, and the sage Mpu Bharada defeats her by having his disciple marry the daughter and borrow her book of magic. Bali's Rangda is Calon Arang in her graveyard form.

What is a balian?

A Balinese traditional healer. A balian usada works from the lontar texts with herbs and formulae; a balian taksu works in trance and is consulted to find hidden causes of illness. Many people consult both, and a clinic as well.