I have a question about casting "Create Pit" in an area where "black tentacles" has been cast. 2 PCs are grappled by the black tentacles, the wizard casts create pit as a clever way to break the grapple to free the pcs. They fall 10 ft by choice of wizard not to make it 30 feet... Does this work? Or do the Black Tentacles go with them to the bottom of the Pit? Thanks...