Loki learned that Malekith had the Casket, and asked Wasp for her help retrieving it. Wasp made up a team with some of the Avengers, and was able to recover it, but fearing what Loki would do with the artifact, Wasp gave the Casket to Moon Knight to hide.
Once again Malekith was able to learn were the Casket was, and stormed Moon Knight's hidden warehouse to steal the artifact for himself yet again, he was attacked by Angela who was apparently tracking him, but was able to escaped with the artifact in his possession.
After finally being able to stay in possession of the Casket of Ancient Winters Malekith moved forward with his plans. Malekith decided to conquer Midgard by creating a state of Eternal Winter with the help of the Casket's power and his army of Frost Giants and Dark Elves.