Sigil of Thanatos

The Sigil of Thanatos, also known as Thanatos the World Bane, was a machine that was noted as the greatest superweapon that was ever created.

The Sontaran Snathe searched for the weapon in order to return glory to his name. After encountering The Doctor, he claimed he would help the Sontaran find the machine. It produced the Inuk to serve as antibodies for itself and was intelligent enough to herd enemies into traps.

It was capable of probing people who approached it through tentacles that interfaced with the individual on a mental and physical level. A judgement engine inside the machine also decides on whether to exterminate a race or not; it determined whether a species was at an evolutionary dead end or were capable of self sacrifice. (CS: The Betrothal of Sontar)