When Ant-Man and Wasp were pulled into their realm, he fought the Frost Giants with an axe he picked up while she was unconscoiuss. He nearly won until Ymir had opened the Casket on him causing him to freeze. Before Ymir and his warriors were about to kill him, Hank had confessed that he loves her and then was about to punch the Frost Giant leader until Lady Sif and her Valkyries had swooped in and rescued him and Janet.
It is also part of Loki's conquest of all of the remaining realms. But when the Avengers had defeated Loki, Jotunheim was free as were the other realms.