Guarding Dark

`Indeed. But I think you misunderstand. I am not here to keep darkness out. I'm here to keep it in.' There was a clink of metal as the shadowy watchman lifted a dark lantern and opened its little door. Orange light cut through the blackness. `Call me ... the Guarding Dark. Imagine how strong I must be.'
The Summoning Dark backed desperately into the alley, but the light followed it, burning it.
And now,' said the Watchman, 'get out of town.'
(c) Terry Pratchett