All you really need to know about “The Northman” — a $90 million Viking revenge saga directed by Robert Eggers — is that every single minute of it feels like a $90 million Viking revenge saga directed by Robert Eggers. Both parts of that equation are worth celebrating outside of and in addition to the movie’s other merits.
Even if “The Northman” had been a dreadful bore — and not a primal, sinewy, gnarly-as-fuck 10th century action epic that starts with a hallucinogenic Viking bar mitzvah, features Björk’s first narrative film performance since “Dancer in the Dark,” and ends with two mostly naked men fighting to the death atop an erupting volcano — the simple fact that financiers had the…