Devon Seltzer’s review published on Letterboxd:
Set in that special time when all samurai films are set, a misty feudal Japan full of honor and ninjas, The Magic Serpent presents us with a pretty standard revenge story spiced up by magic and monsters. Lord Ogata is a kind and peaceful ruler who is betrayed and killed by his trusted general, Daijo Yuki. Ogata's son, Ikazuchi-Maru manages to escape the coup and trains in the ways of combat with an old monk in the woods before setting off to reclaim his father's land.
While I was forced by availability to watch a poor quality dub of the movie, I don't really feel anything was lost in translation. The story is nothing special, being conceived as a very loose retelling of the Jiraiya folktale, and playing out like your standard samurai revenge narrative. The film contains all of the elements that are fun to mock about old martial arts movies, with sharp cuts and corny sound effects. Meanwhile, the cast plays everything just right, giving hammy performances worthy of the material they are working with.
Sadly, despite the presence of samurai, ninjas, magic, and monsters, The Magic Serpent is rarely exciting, often feeling like quite the slog to get through as we are given a poor ratio of cheesy action to clunky dialogue. When they do occur, the action scenes are fun, but nothing special, though the run-of-the-mill fights are buoyed by the use of magic, allowing for moments where someone's severed head can aid in a fight or a room full of doors turns into a dangerous foe.
I have mentioned monsters a couple of times, and there is a reason why this movie is part of my giant monster marathon, it deviates from many of its contemporaries by including not one, but four plus-sized beasties for you kaiju stomping pleasure. Don't get too excited though, because these are bargain bin monsters to be sure. The effects are less then impressive, and the use of the monsters is pretty sad, with the main fight scene between a dragon and a giant frog amounting to little more then a prolonged hug. Those are by far the most interesting monsters, though a large bird and a large spider show up briefly as well. One odd thing worth mentioning about the monsters in The Magic Serpent, with the exception of the spider, they all steal the voices of well known Toho kaiju. The dragon bellows with Godzilla's signature Showa roar, the bird chirps in Mothra's tongue, and the frog belts out Rodan's famous call. It was both hilarious and jarring to hear these familiar cries coming out of completely different monsters. I wonder if someone got sued.
Despite some nice touches, overall The Magic Serpent is just too slow and generic to really impress. The presence of the monsters, however underused they are, and the addition of magic, do make for some fun moments, and there is certainly a joy to be found in this kind of campy strangeness. Still, watching a frog and a dragon smash a castle can only take a film so far, and while nothing in The Magic Serpent is awful, nothing is quite amazing either, meaning this film left me lukewarm, somewhere between burning frog fire and freezing dragon water.