MultiBlend
MultiBlend is a shader found in newer versions of Source (Alien Swarm). It allows for blending only on displacement surfaces using up to four different materials.
The texture preview in hammer requires you to set up additional VMT files for each texture to show up in the dialog. Those are not used by the shader itself.
Note:Although present in the Alien Swarm version of Source, this shader does not seem to fully work and renders fullbright in-game.
Deprecated:This shader should not be used in 
Counter-Strike: Global Offensive, use Lightmapped_4WayBlend instead.Example
MultiBlend
{
$basetexture nature/grass_00c
$spectexture nature/grass_00a_spec
$scale 1.5
$rotation 0.0
$basetexture2 nature/sand_cracked001
$spectexture2 nature/sand_cracked001_spec
$scale2 3.0
$rotation2 0.0
$basetexture3 nature/sand_path001
$spectexture3 nature/sand_path001_spec
$scale3 3.0
$rotation3 0.0
$basetexture4 stone/stone_path007
$spectexture4 stone/stone_path007_spec
$scale4 3.0
$rotation4 55.0
%tooltexture test/terraintest-1
}
