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 a DC 16 Wisdom (Insight) check 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).