I wanted to have Samus charging up her laser beam. I went ahead and slapped a Beam affect on her. I made the start point her gun and the end point just off screen so it was faux 3D. Then i just adjusted the length and timing to where I wanted it.
Then I needed my little charge up particles.
I wanted little power spheres, so I went ahead and made my particles faded spheres after trying both bubbles and shaded spheres. I matched the color to the lightest part of the beam. My rate was only .2 per frame and my longevity was about half a second. I didn't want there to be much coming out of the gun, just a slight effect of charging particles. For the motion I ended up using the twirly and adjusted the camera position, so that they looked like they were spreading out from the gun rather than falling out. Then I adjusted the emitter position to line it up with the barrel of her cannon.
Boom! I'm a firing my laser!
Untitled from William Maddox on Vimeo.