Fuse is a replacement for the merge(over) node.
"Light Flare” : wraps a luma keyed background over the foreground. Only the brighter parts of the image are wrapped.
"Wrap All” : wraps all of the background values over the foreground.
"Bleed Color” : wraps hue values from the background over the foreground. It replaces foreground hue values with background values.
"Edge Blur” : blurs the edge areas of the composite. This edge is determined by alpha transparency. So any parts of the alpha that are semi-transparent will be blurred.
"Apply operations in Log” : will layer the foreground over the background in a Log colorspace resulting sometimes in a preferable result.
