Traveling through time and space is not something to take lightly. If you're not careful you could end up in the middle of a war zone swarming with futuristic killing machines. Machines that can't be bargained with or reasoned with, that don't feel pity, or remorse, or fear. Machines that absolutely will not stop, ever, until you are forced to regenerate.
Tags: doctor-who, drwho, sonic-screwdriver, time-travel, science-fiction