How to mask sprites/animations using alpha channel

Hey, I have been experimenting with unity for some time now and I came upon a simple(?) problem. I have a compound sprite with some of its parts animated. I want to make an overlay animated sprite roughly in the shape of the original sprite from a generic animation. Specifically, I'd like to create an energy-shield effect. Have a character/vehicle/etc. and flicker some colors over them.

I have thought of making a plain rectangular sprite with the desired animation frames, create a clone, position it over the character and then use a pre-defined alpha mask (in the shape of the character) to "cut" the shield in the shape of the character.

Is this thing possible to make such thing programmatically? is there a better way of making it? I'd like to avoid creating dozens of identical animations/textures with just different shapes.

thanks.