Light Vector/Material Editor

How do I regain the functionality of this node in the material editor?
I just want to do something that should be relatively simple. Create a Blinn approximation and pop it into my emissive channel on a translucent material. I just want some cheap water. I have been looking at other people’s shaders but they are overwhelming to sort through.

In UDK I would have just:
((((CameraVector + LightVector)0.5 <normalize>) dot Normal)^Tightness)Brightness

But using a light vector is now illegal. How can I get around this?

Not at all. There is no way to access the light vector in a material with deferred rendering.
What many people doe as a workaround is to use Blueprints to calculate a light vector from a certain light source(e.g. directional light/sun). For a water material this should work well enough.

I see. Thank you!