Place it at the end of a reveal, after sudden suspense builds the tension and just before Nelson's Ha-Ha answers it with mockery. That order gives a villain moment a setup, a payoff and a taunt, without crowding the scene.
About this sound
This is a short, theatrical evil laugh lasting about four seconds, with a deep, rising cackle that sounds delighted by someone else's misfortune. It feels menacing and gleefully cruel, the kind of laugh that makes a villain's triumph land instantly. It comes from Tales from the Crypt, season five, episode one, Death of Some Salesman.