'jig rten thams cad

...are the present day term for what is called a "wheel" in the Tibetan. A "wheel" as a weapon, being a disc, its rim composed of sharp spikes. It is hurled at an enemy. It is said that Songtsen Gampo had such weapons but of immense size. He banned their use due to the extensive destruction they caused. This "weapon-wheel" or "death-star" plays a prominent part in the sadhanas of many Wrathful Deities and Protectors, often forming a dais upon which they are situated, or even being their palace. Peter Roberts