Don't know if it reveals anything in season 4 im in england season 4 not started :(

But wot i think happened was usually when lilith did that bright light thingy everyone around her dies. Just like in Jus in Belo. But I think some part of Sams physic powers makes him immune to her. Thats why Lilith is so shocked and scared

Anways thats what i think, propbably wrong :)