Archangel of Pain

The Archangel of Pain is a Drukhari artefact which takes the form of an ornate cask that holds the essence of a captured Daemon. When released, these entities flee back into the Warp, their soul-rending psychic screams driving those that hear them irredeemably mad.

In the days before the Fall of the Aeldari, the prophet Ynshimael sought to save himself by crafting a device to trap daemonic entities.

Ynshimael's artifice was clever yet inadequate in the face of Slaanesh's birth, and his soul was devoured in seconds following the awakening of the Chaos God.

Since those days, the device has been perverted by Ynshimael's Commorrite successors, becoming the metaphysical prison known as the Archangel of Pain. It is used to trap Daemons, binding them in a pit of barbed nothingness that tears and tortures their empyric substance, so they can be used as a potent weapon against the Drukhari's foes.

Sources

Codex: Dark Eldar (3rd Edition), pg. 16
Codex: Dark Eldar (5th Edition), pg. 60
Codex: Dark Eldar (7th Edition), pg. 109