Blood control

Blood control is a method of controlling an entity's actions via their blood - for example, a sample of A+ blood would allow a ship with sufficient technology to control all Humanity with A+ blood from the vicinity of Mars. However, blood control does have its limitations; like hypnosis, blood control could not make someone do something they did not want to do (such as commit suicide).

Not many races seem to have blood control, and the Doctor himself hadn't seen it in a long time. One example of a race with a capacity for blood control was the Sycorax, who would use the blood control as a bluff (if they could) to threaten to kill all the people on the planet affected if half the planet wasn't sold into slavery. (DW: The Christmas Invasion)


 * The Sycorax probably regarded blood control, like other technologies, as a form of witchcraft or sorcery.