I am extremely knew to substance but yes you can use layer blend with substance. Substance creates modifiable textures. The textures themselves are no different then any other texture what makes them modifiable is the factory which you can use to change the texture. Not to sure if you have seen a youtube video about how to use substance with terrain but I am going through it right now and seem to have possibly hit a bug as my material looks fine but the terrain is just black. Still need to look into the possible problem but I hope that helps.