Deepen Shadows

Over the course of a minute, the shadows in one 10 foot cube 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 Wisdom (Insight) check with a DC equal to the spell save DC to notice it. The size of the area that can be affected increases when you reach 5th level (20 feet), 11th level (50 feet), and 17th level (100 feet).