Special effects 101:

Most of the pretty lights and suchs are from 
backlight cels..  those cels you own with black 
paint on the back of them?  ... that's what I am 
talking about.  They paint them black so that the 
light wont shine through the entire cel... just 
where they want it to shine through.  

Sometimes, they simply leave a black spot where 
they will add in effects later.  If any of you 
have a Gourry cel with the Sword of Light... it 
will just be a black blade... nothing white or 
light about it.  They go back in later and add the 
lighting effects.  (and they blooper these a LOT. 
 Gourry will pan off to the left and the blade 
effects stay where they are!  BAD!)

So most of the time... if you have a cel with a 
black ball of what should be pink magic... or just 
a cel where the back is painted black... then you 
already HAVE your special effect layer.  :)

Hope that helps.
Jennifer