The Absorbing Nightmare of “Legion” 

Noah Hawley’s “Legion,” on FX, the latest Marvel production based on the X-Men, has an aesthetic that might be described as caustic whimsy. It’s a sleek, stylized diorama of alarming imagery, as much about fear orange and misery avocado and rage yellow as it is about anything else. You don’t actually have to understand much about the X-Men to enjoy watching it.