Remember, the villain is a dick (to the main character).
Describe every little thing the antagonist can do to keep your character from achieving their outer goal. Figure out how it works in your story, and what’s worth keeping.
Dig deeper and list all the ways the antagonist can pick at your main character’s wounds (inner or external). Why would they want to play a psychological game, specifically?
Keep these things for your outline – the most you explore the characters, the more your story may evolve and change. This is a good thing! Exploration leads to discovery, and you might be surprised by what you find.