“Ghostbusters: Frozen Empire” (**1/2 out of four) was a good-natured if uneven sequel about an ancient artifact that unleashes an evil force in NYC and it’s up to the ghostbusters, both present (Paul Rudd, Mckenna Grace, Carrie Coon, and others) and past (Bill Murray, Dan Akyroyd, Ernie Hudson) to save the day and prevent the forming of a new Ice Age that could overtake all of the city and Earth. Initially plodding and predictable but starts to get going more in its second-half and leads to a spectacular special-effects blowout that will likely send you out with a smile. A definite improvement on the previous “Ghostbusters: Afterlife” but this still bears the mark of going to the nostalgia well once too often. William Atherton and Annie Potts amusingly return in supporting roles.