This extremely odd movie was made at a time when Roger Corman's Edgar Allan Poe franchise was raking in big bucks, but the small portion of Poe's output suitable for cinematic adaptation was fast running out. Corman's typically couldn't-give-a-monkey's solution was to stick the titles of unfilmable works by Poe onto just about anything starring Vincent Price. The basis for this film's screenplay was a poem about a man grieving for his dead wife who becomes even more depressed after a raven flies into the room. Since that's literally all that happens in the source material, Corman had to fill a gap almost as large as the entire movie, so naturally he turned a poem about morbid grief into a borderline Pythonesque comedy revolving around Peter Lorre's transformation into a very disgruntled bird.
In a pseudo-rennaissance fantasy realm where magic is seemingly part of everyday life, though we see nothing of the world beyond the main characters' homes because Corman can't afford to show us anything he doesn't have to, three wizards, the gloomy Craven (Vincent Price), the drunken Bedlo (Peter Lorre), and the sinister Scarabus (Boris Karloff), come very close to delivering a low-budget parody of "The Good, the Bad, and the Ugly" in Shakespearean drag with magic instead of guns five years before it was made. With slightly more money behind it, and a director who, unlike Corman, really understood comedy (we're talking about the man who edited "Death Race 2000" to ribbons because he didn't see why it needed any jokes), it might have been an offbeat masterpiece rather than the self-indulgent yet strangely enjoyable muddle it ended up as.
It's not a great film, or even a particularly good one. However, it's fun, and that excuses almost anything. No excuses are needed for the gleefully ramshackle magic duel whose special effects aren't anywhere near state-of-the-art even for 1963, because by that point it's all gotten so silly that it's essentially a live-action cartoon, although unfortunately a more cartoonish pace is the one thing it needs most. Most of the cast are obviously enjoying themselves immensely. Vincent Price and Peter Lorre in particular seem to be having a ball.
Boris Karloff sometimes looks a little uncomfortable, but he's the bad guy so we're meant to take him at least half seriously. As for the others, no such limitations apply, and they know it; femme fatale Hazel Court can barely keep a straight face. The young couple who always have to be in films like this even if they're a waste of space are a waste of space, but it's unintentionally hilarious to see an incredibly youthful Jack Nicholson, overawed by the more stellar members of the cast, self-consciously fading into the background. And watch for the first awkward try-out of his trademark "Heeeere's Jackie!" grinning maniac routine.
I'm surprised Roger Corman thought a sub-genre so small it consisted almost entirely of his own Poe films was big enough to need spoofing, but spoof it he did, though I noticed that the original cinematic trailer included as a DVD extra tried to disguise the fact that it was a comedy, as if even American International Pictures were baffled by their own movie the moment they saw the finished product. But speaking personally, I don't think "Doctor Strange" would have been a worse movie if it had included a few levitating armchairs and a spell that turned people into raspberry jam.
PS - Roger Corman finished this film ahead of schedule and everyone involved was still under contract for the next few days, so he made another movie using a script written literally overnight. The result was "The Terror", which truly has to be seen to be believed!
PPS - "The Raven" (1963) has no connection with "The Raven" (1942) even though Boris Karloff's in both of them.