Tardis Dream Crabs

The Tardis Dream Crabs were originally normal dream crabs that started digesting the inside of the main console, as they did that they released an immense amount of Artron Energy which mutated them and bonded them with the Tardis Console and extended their abilities, so that when the Doctor and Jack did as little as touch the console, the dream crabs sent them into a dream. This dream contained the same dream crabs which sent them into a further dream, this happened several times before Jack realised that so little as a death could end a dream, so they both manipulated the dream to form a hitman to come and kill them, waking them back up into reality, the Doctor isolated the Dream Crab’s abilities and slowly suffocated them.