The Skull Truck is the largest of the Skulkin vehicles. It is a skull-faced monster truck with moving jaws and a bone hand on its rear. The latter was the vehicle's main weapon, and could be launched on a chain to grab and pull objects. It has room for multiple Skulkin, but appears to be fully functional with as few as two riders - one to drive the truck, and one to man the bone hand.
The Skull Truck was used as the Skulkin Generals' personal transport for the attack on Four Weapons Blacksmith. During the battle, Kruncha fired its bone hand at Nya, taking her captive. With a prisoner secured and their true objective (finding the map to the Golden Weapons) complete, Samukai returned to the truck and ordered a withdraw.
After the Skulkin obtained the Scythe of Quakes, Nunchucks of Lightning, and Shurikens of Ice, Samukai and several other skulkin boarded the Skull Truck to return to the Underworld. However they were pursued by Cole, Jay, and Zane and after an intense chase, only Samukai, Kruncha, and Nuckal managed to cross over to the Underworld in the vehicle.
When the Ninja arrived in the Underworld, the Skull Truck was parked next to entrance of Garmadon's fortress.