Usually, this kind of effects are the result of post processing so treat it as such. My advice would be to make a circle (blur it if you want) and set it to a blending mode that resembles the effect you want to give. Animate any lighting effect that you may want to have in said layer and lastly be careful when using the eyedropper tool to pick colors from this layer, you may end up sampling all layers instead of the current layer.
