Take now the Pen Tool and insert on a new layer, above the dragon's one a white flare (grouping them preliminary):



Blur it out a little, selecting the next combination: Filter ? Blur ? Gaussian Blur.



Change the dragon's layer Blending Mode on Lighten:



Select now the Gradient Tool of a darker color than the background is and paint the picture's edges on the layer, above the rays:



Change now the layer's Blending Mode on Soft Light and minimize the rays' layer Opacity till 90%. In the Blending Options on the dragon's layer we'll add the adjustments Outer Glow, just to place the dragon on the first plan: