Civil procedure is tricky (non-mutual offensive collateral estoppel, res judicata, interpleader, you get the picture), but with this supplement you're almost guaranteed to stay ahead of the curve.
The author also does Barbri videos, which are helpful in getting a general sense of the major topics covered in 1L civil procedure courses. This book, on the other hand, covers the coursework of Civil Procedure 1 & 2. The book is thorough (without droning on) and explains complicated concepts in a clear and understandable way. It's worth every penny.