The Ar'Ka Cannon is a unique weapon of Tau design that was constructed on Nan Yanoi ("Sword Moon" in the Tau Lexicon), one of the two moons of the world of Kaurava II in the Kaurava System. The Ar'Ka Cannon was an integral part of Tau Commander Shas'O Or'es'Ka's strategy that translated into Low Gothic as "Great Strength, Great Strike" to conquer that star system. Tau Earth Caste engineers had constructed the weapon on Nan Yanoi, and the cannon was capable of striking any target within the star system. The Ar'Ka Cannon fired a concentrated "Ion Beam", which was tuned to a frequency and wavelength that only destroyed the central nervous systems of advanced organic life forms, and ignored plant life and inorganic structures. This allowed structures and plant life to remain, allowing the Tau Empire to strike at their enemies in the system without wreaking too much damage to the environment of the system's habitable planets, thus retaining the targeted location's suitability for future Tau colonisation. The cannon could fire its beam at any point on the surface of any planet in the Kaurava System. This weapon was unique, and the Tau built extensive fortifications at the base they established on Nan Yanoi to guard it. A modified version of the Ar'Ka Cannon was mounted on satellites orbiting above Nan Yanoi, which acted as a defence mechanism if any intruders made it past the orbital cannons and landed on the moon.
- Dawn of War - Soulstorm (PC Game)