Refraction based on mesh shape

I’ve created a crystal staff in blender and used the transparency settings to create a refraction. I would like to recreate the way the light is refracted in UE. Currently, I have it set up so that it does refract light but not in the way a prism would. From what I understand, I am supposed to change the normal on the texture but I’m not sure what to input. What steps would I use to reproduce this effect or at least make something similar?

I would also like to fix the viewing problems caused by making part of the mesh semitransparent. Would I have to edit the mesh on blenders end to include an extra face?