As you can see from the still, it enables you to create a pool of light as from a spotlight, or even just a slash of light across the image - again something you could easily enough do with the color corrector now, but this has the added advantage of being able to add a glow, which I think makes a lot of difference to the effect.
You have controls for:
- position of the four corners of the 4-point mask that shapes the effect, also via onscreen controls;
- roundness, feather and fall-off of the shape;
- brightness On/Off and amount;
- Tint On/Off, color and intensity to control the colour of the "light source";
- Glow On/Off, radius, opacity, threshold and softness.