Ask questions. Ask them what it looks like when they open their brain, what they do to reach that state and what has occurred in the past.

I’m not saying have the players make everything up. I don’t like saying, “You open your brain, what does the Psychic Maelstrom look like?”

I’m saying, “What does Brainer do when she opens her brain?”

Maybe they mentioned that they came from some kind of government instillation with barracks full of psychics. “What is the worst thing you’ve seen happen to a brainer who was careless with the maelstrom?”

Ask good questions that give you a shape and fill in those details.