Deepen Shadows

Over the course of a minute, the shadows in one 10 foot × 10 foot or smaller area grow larger, deeper, and more concealing. A room that is brightly lit becomes dimly lit. The change is so gradual that it requires Wisdom (Insight) check versus your spell DC to notice it.

The size of the area that can be affected increases when you reach 5th level (20×20), 11th level (50×50), and 17th level (100×100).