Your comments

I'm using Unity3D Indie so forward render, i will try the static thing :) 
No, it's a voxel terrain, and yes i think they are quads, they are also merged in groups
Hi Joachim, you can put this as a completed since it's done, i don't know how to do it, or how to close a thread.
Thanks and apologies.
I think this is a good idea, since the new UI of Unity uses stencil shaders.

I don't want to create a new topic for not mess, but it will be cool if this tag is added to the Shader Forge menu :

Tags

{

"PreviewType"="Plane"

}

This allows the shader window to be a plane everytime.
Hi there is a way for use Shaderforge with terrains, look at this images:

Agree with him a loop node is very important.
It works perfect i will leave it here 
Ahh i'm going to try it, thanks Joachim ^^!
Yes, for reproduce the bug you only need to drag an drop a splatmap from terrain asset.