Probably the most propitious is the alliance between Proctor and Hood, after Proctor burns down Hood's house in the woods. Proctor's entitled, I guess, seeing as how Hood reneged on his promise not to bed Rebecca, though who other than Proctor could blame him. But it makes perfect sense that Proctor would want Hood on the case now, and reporting to Proctor, the minute the killer comes into view.
This complicates the other good alliance of the evening, Hood and Veronica. Proctor wants Hood to bring the serial killer to him, and not leave the killer in the hands of the FBI. Obviously Proctor wants to do more to this monstrosity than just kill him. Presumably Veronica would have other ideas - though you never know, given her unconventional ways.
But speaking of monstrous, that neo-Nazi Randall just released from prison was a vicious piece of work, and it was good to see Calvin suddenly kill him, after Randall threatened, taunted, and ridiculed Calvin, and stirred up the crowd, and Brock prevailed upon Kurt not to sniper-shoot him in the head. The upshot is that Calvin is pretty tough after all, and may be harder to beat than his late brutal father-in-law.
Job is back to his reassuring looks and self, and tells Hood an interesting piece of news about Carrie that I don't recall before this: she's determined to avenge her husband's death and blames Proctor for it. This puts another complication in Hood's alliance with Proctor - not really an alliance, I guess, but something like that. Fortunately for Proctor, Clay seems to be in the best, most astute shape we've ever seen him.
Banshee has always been about complications, and they're piling up quite well in this final season.
See also Banshee Season 4 Debut: Whunnit? ... Banshee 4.2: Carrie and Rebecca ... Banshee 4.3: Serial Killers and Theories
And see also Banshee 3.1: Taking Stock ... Banshee 3.2: Women in Charge ...Banshee 3.3: Burton vs. Nola ... Banshee 3.4: Burton and Rebecca ... Banshee 3.5: Almost the Alamo ... Banshee 3.6: Perfect What-If Bookends ... Banshee 3.7: Movie with Movie ... Banshee 3.8: What Did Rebecca Find with Burton? ... Banshee 3.9: Loyalty ... Banshee Season 3 Finale: Subtractions and Additions