Prudence may be Blackwood's daughter, but they're far from alike, and she proves it by hunting down her evil father and keeping him from sacrificing her half-siblings. Her friendships with Dorcas and Agatha are strained this season, even more so when Agatha is driven to madness by a pagan god. Agatha joins forces with Blackwood and kills Dorcas, an event that Sabrina can't reverse when she time travels. In a fit of rage, Prudence blames Ambrose for Dorcas's death because he didn't let her kill Blackwood when she had the chance.
By the end of the season, we see her and Nick comforting each other on the steps of the Academy in the wake of their respective breakups.