Disolve Shader - Shader Graph

I started with a simple dissolve using a texture as input for the dissolve pattern so we can do more fun things later.

First I take the Sin of Time and map it to 0-1 so it oscillates between black and white.  That drives the alpha cutoff value for the texture.  For example.  Here the effect is taking 2 seconds.  At 1 second (halfway) anything darker than 50% gray will be transparent.  As time moves forward, more and more becomes transparent, following the lightness of the source texture.

Now let's apply a color to the edge of the dissolve.  To do this, I add an Edge Thickness property.  This is a float, set here to 0.1, which is added to our Time variable.  That new, slightly ahead, time node is used to get us the same as the above alpha, but slightly leading what we see above.  This leading edge can be tinted some color and passed into the emission property so  the edge glows.

To do a multicolor edge, I just cut the edge thickness in half and do the same thing we did above again, giving an edge that's between the alpha and the leading color.  Then combine the two.

From here, the magic is all in the textures.  Let's see some examples of how different textures and colors look.

If you combine a gradient with your noise, you can control the direction of the dissolve.

You can even hide images or text in there.

All textures originally from: https://opengameart.org/content/700-noise-textures