The Darchala's Chaos Device is an artifact found in both Heretic and Hexen. When used, it sends the player back to the start of the level (or near a portal the player came from in Hexen). It is best used to get out of unpleasant or dangerous situations. The figure featured on the artifact closely resembles the "symbol of chaos" designed by Michael Moorcock.
In Heretic, if the player holds a Chaos Device when he is hit by the powered-up projectile of the Firemace (whose contact is normally lethal), the device will trigger automatically to save the player. However, the player will still lose half his health.