So, it seems the mobs can and do cast every spell available to players aside from sneak and invisible. Why is that? Some should be able to cast sneak/invisible too. You could have weaker mobs using it to try to avoid you. Or NMs trying to hide from you. Or tougher mobs using it to sneak up on you. Just think of the possibilites!!
Just imagine walking along, and you see just footprints coming towards you... You think it's just another player when -BAM- it becomes visible and attacks!