I'm trying to get the following effect, but as far as I know, a filter is the only sensible way.
Imagine some objects and background, and a fire ball passing through. The fireball glows. All objects (not the background) become brighter in color where they are under that glow. The glow effect could be described as a glow around a missile's fire.
This should be built-in to Phaser, as pixi.js has it.