The Heart of the Mountain was a crystalline artifact connected to a war machine walker on Skara Nal. Inserted into a socket within the walker's control room, it kept the vehicle inert and inactive while it was buried inside a mountain. As Skara Nal was remembered in pirate legend, the Heart of the Mountain was believed to contain great power and hold immense value. Phee Genoa attempted to claim the Heart of the Mountain when she discovered the walker alongside the Bad Batch between 19 BBY and 18 BBY, but the superweapon's activation upon its removal and ensuing rampage placed the group in danger of being stranded if their ship was destroyed. Genoa was thus persuaded to return the crystal, deactivating and destroying the walker but also melting the Heart.