The dementors are "soulless creatures.. among the foulest beings on Earth": a phantom species who, as their name suggests, gradually deprive human minds of happiness and intelligence. They are the guards of the wizard prison, Azkaban, until after the return of antagonist Lord Voldemort. Albus Dumbledore harbors an intense dislike of dementors, noting he has long felt the Ministry of Magic erred in "allying" with such creatures, implying that dementor society in general exists apart from the general wizarding world. Dumbledore forbade dementors from entering Hogwarts but this ban was ultimately broken. dementors have a generally human shape, approximately 3 metres (10 feet) in height, covered in dark, hooded cloaks that reveal only their decayed-looking hands. Beneath the cloak, dementors are eyeless, and the only feature of note is the perpetually indrawn breath, by which they consume the emotions and good memories of human beings, forcing the victim to relive its worst memories alone.  dementors grow like fungi in dark, moist places, creating a dense, chilly fog. Although they are implied to be sentient, this is left ambiguous. The presence of a dementor makes the surrounding atmosphere grow cold and dark, and the effects are cumulative with the number of dementors present. The culmination of their power is the 'Dementor's Kiss', wherein the dementor latches its mouth onto a victim's lips and consumes its soul or psyche, presumably to leave the victim in a persistent vegetative state, without any memories and feelings left. Dementors are invisible to Muggles, but affect them otherwise identically. Despite their attachment to human emotion, dementors seem to have difficulty distinguishing one human from another, as demonstrated by Barty Crouch Jr.'s escape from Azkaban, wherein they could detect no emotional difference between the younger Crouch and his mother. Their sensitivity appears less precise in proportion to the emotion's 'complexity'; this particular weakness enabled Sirius Black, an Animagus, to escape Azkaban by transforming into a dog. The principal method against them is the Patronus Charm, which both protects its user and repels the dementors.