Mjolnir is the mythical weapon central to Tomb Raider: Underworld.
In Underworld, Lara searches for the Norse hammer Mjolnir while investigating ancient Norse myths and the disappearance of her mother. The hammer is presented as a powerful relic connected with Thor, the thunder god.
Mjolnir is easy to confuse with Excalibur, which is the major artifact in Tomb Raider: Legend. The Scion belongs to the original Tomb Raider, while other legendary weapons appear in separate games and adaptations.
Underworld continues the story begun in Legend and Tomb Raider: Anniversary. It was developed by Crystal Dynamics and released in 2008, concluding that trilogy's main arc about Lara's family and the ruins of Atlantis-related mythology.