Born from the fiery remains of the Phantom Ship, the Mammoth Bosquito, an immense two-headed creature, emerged from a flash of crimson lightning that jettisoned from the ship's detonated hull. While the monster glided down from the cloud sewn sky to the Earth below, Takuto Ando was the first to act against the creature as he quickly dived into the Great-Lio and prepared to confront this new challenger head on. However, despite initial appearances, as the 52 meter mech stood almost shoulder to shoulder with his opponent, the Mammoth Bosquito quickly turned the tides in its favor as the monster absorbed the remaining Bosquito forces and increased its own size by several fold.

Witnessing the transformation, the other Sazers and Justirisers proceeded to dive into their own mechs as Garuda, Dorcrus, GunCaeser, Leviathan, Ken Riser, Nin Riser and Ju Riser joined the fray. Unfortunately, despite their combined efforts, the eight warriors were powerless against their gigantic adversary as he quickly rained his red hued lightning down on them while Dorcrus and Ju Riser's combined firepower was effortlessly absorbed by the Mammoth Bosquito's barrier. Undeterred, the Great-Lio rushed his foe in an attempt to strike the Mammoth Bosqutio with his blades; unfortunately, the attacks were once again rendered unsuccessful by the monster's barrier, as the Great-Lio was merely kicked away from the creature. Expanding its offensive, the monster then latched its jaws around the much smaller Great-Lio while simultaneously attacking Garuda with its enormous clawed hand. The other warriors could only watch on while the Mammoth Bosquito picked up the Great-Lio and tossed into Ken Riser, knocking them both to the ground, while it continued to strafe the rest with its crimson lightning beams.

Despite being terribly outmatched, though, hope was not lost, as the Gotengo sallied forth to join the battle and start its own offensive. Not wasting anytime, the craft begin to discharge its Zero Cannon, freezing the Mammoth Bosquito outright as the other warriors watched in awe. With their enemy paralyzed, Garuda and Ken Riser sprang into action, leaping up to the creature’s heads to severe its horns, removing the barrier in the process. Following the attack, the creature quickly thawed from its frozen state, and was once again mobile to continue its attack. However, with its barrier removed, the monster provided little challenge for the warriors, as their combined efforts severed one of the giant heads and clawed hands while they punctured holes through its wings, halting its ability to fly. With the Mammoth Bosquito in critical condition, the Sazers and Justirisers released their energy into Takuto’s Lio-Javelin, greatly magnifying the weapon's potential, as it was able to disintegrate the Bosquito in a single strike, ending their reign.