Kylo Ren's lightsaber was a crossguard blade constructed and utilized by Kylo Ren approximately thirty years after the Battle of Endor. The lightsaber was crudely assembled based on an ancient design dating back thousands of years to the Great Scourge of Malachor. A single cracked Kyber crystal, barely able to contain the weapon's power, necessitated the lateral vents which diverted the extra heat produced by the crystal to either side of the hilt, and gave the weapon's red plasma blades an unstable, serrated appearance. Kylo wielded this weapon while working alongside the Knights of Ren and the First Order. The lightsaber was used to murder Church of the Force member Lor San Tekka, and Ren's own father, and later crossed blades with the lightsaber that formerly belonged to the Skywalkers; Ren defeated and injured the former stormtrooper known as Finn in the duel, but was overpowered in the ensuing duel with Rey.