The Casket of Ancient Winters is powered by a limitless supply of magical energy. When opened, it releases powerful arctic weather that is capable of freezing anything in its path; killing humans and immobilizing Asgardians. The Casket can only be opened and handled by a Frost Giant; anyone else who attempts to open it would be burnt by the powerful cold aura that surrounds it. Its magic is also strong enough to temporarily disrupt the powers of Odin.
In the film, the Casket is used by the Frost Giants in an attempt to take over the Nine Realms, starting with Earth. When the Frost Giants are defeated by Odin, the All-Father takes the casket back to Asgard for safekeeping. He later displays it to his two young sons; Thor and Loki, when he is telling them stories about the war with the Frost Giants.
In the late 2000's, a party of Frost Giants, with the aid of Loki, tried to steal the Casket but were vaporized by The Destroyer. When Loki discovers his origins as Laufey's son, he takes the Casket for himself; once he gained the throne of Asgard, he uses the power of the Casket to freeze Heimdall, who was opposing him as a ruler. It is unclear what became of the Casket after Loki fell from the damaged Bifrost bridge and into the abyss.
Powers and Abilities
The casket is powered by an apparently limitless supply of magical energy. When opened, it releases powerful arctic weather that is capable of freezing anything in its path, killing humans and immobilizing Asgardians.
