The Chest of Rage is an artifact in King's Bounty: The Legend.  It is also known as Pandora's Box.

It is obtained in the quest A Secret Weapon, and given by Master Trigius.  It is a demon's creation, obtained a thousand years ago by King Kerus among other trophies.  Since then, mages have spent almost a thousand years trying to solve its mystery, and only revealed a part of the secrets the artifact hides.  The mages in the Verlon Forest magic academy have figured out how to tune the artifact, and performed a ritual that activated the symbiosis component to attack itself to the one who closes the chain of rage.

In the words of Zerock, it is a weapon - designed to capture those who are strong.  It uses the strength of the captive as a weapon on others.

Reaper gives information abou the chest - previously owned by ARchdemon Azazel, the pilgrim Garmah, Maser Vayen, Archdemon Baal.

In the story, the main character injures his hand as he fumbles with the chest. This causes him to bind himself to the chest.

The Chest of Rage contains four major spirits: Zerock, Sleem, Lina and Reaper.