Combines all inputs into one single output following the operation pattern.

• Add: Adds together in a simple sum.
• Max: Gets the maximum value of all inputs.
• Min: Gets the minimum value of all inputs.
• Height Based: Uses a technique to blend the values according to their height, applying a smoothness amount defined by the BlendFactor. This mode is normally used to blend different textures according to their height map, which allows for a smoother transition between them. However it can also be applied into height maps itself. see references
• Normalized Multiply: Will first normalize all inputs into the range of 0 to 1 and then multiply them together. The output will be in the scale of 0 to 1. Recommended to, if needed, remap the range to the desired Minimum and Maximum Value

References

Height Blending Shader – Untitled Games

Many of the shaders I find myself writing require some sort of blending between textures. The most common example of this is for terrain shaders, or shaders for terrain type objects...

http://untitledgam.es/2017/01/height-blending-shader/