Projected Shadow Reverse
By reverse shadow, you can highlight some area instead of darken scene. This trick is useful to simulate dynamic lighting of spotlight, like searchlight, flashlight.
To get reverse effect, you can check light's 'Reverse' style
or check mobile's 'Projected Shadow - Reverse' style
But check two 'Reverse' at same time will get normal shadow effect.
If you use a mobile to produce reverse shadow, maybe you want itself invisible, 'No Render' style is for this purpose:
illustration of search light implementation: