Why cats pounce and stalk?
Pouncing, Stalking and a Cat’s Natural Instincts
Pouncing and stalking behaviors are perfectly normal for cats. Don't be afraid when your cat performs these actions. It doesn't mean that she's angry or wild, nor will it encourage aggression.
Scratching and Biting
That said, if your cat does bite or scratch you during play, stop whatever you're doing and try something different. This will let your cat know that scratching and biting aren't acceptable, and will also ensure that you're not continuing an activity that your cat finds threatening or unpleasant.
Hopefully this brief intro to your cat’s instinctive behavior will help you understand her actions.