Nightfall
Sage of the Scarred Lands
Storm and Core are right, scrying takes a focus or a point to focus on. If the party is moving at random, hard to find them without divine or supremely powerful beings involved. As for Teleport, even with Teleporting without error, there's ALWAYS the chance something can go wrong. I mean you are talking about magic that can go around. Magic isn't a science folks, no matter how much people practice it. Stuff CAN and often does go wrong. Make sure you show that in your games. (I know I do when it comes some spells.)