Once upon a time, I asked Frank Mentzer (on his Dragonsfoot Q&A thread) who came up with this monster. I explained it was one of my all-time favorites from classic D&D. When he graciously answered my query, he said it was most likely Cook or Moldvay. He also wanted to know what it was that I liked about the creature. My reply was quite simple, which I will quote below:
"It's a HUGE, MIND-CONTROLLING WERE-PIG!!"
Let us pause for a moment to let that sink in.
110% Pure Win.
So! Lets look at my incredibly detailed thoughts one at a time, shall we? But first, here are the stats:
No. App.: 1-3 (1-4)
AC: 3 (9)
Move: 180' (60')
-Human: 120' (40')
Attacks: 1 gore (or weapon)
Damage: 2-12 (or by weapon)
Point the first: It's HUGE
Devil Swine are by far and away the scariest of the classic lycanthropes, IMO. They have 9 hit dice. NINE! That's averaging 40-odd hit points. They transform into huge boars that "...are carnivorous and especially fond of human flesh." So it goes out of its way to eat people. In the Labyrinth Lord rules, the "Demon Boar" is described as 9' long. Here's a pic to give you an idea of what that might look like.
Yes, that's a real photo.
2nd point: MIND-CONTROL
The DS can use a potent Charm Person ability up to three times per DAY! What's more, saves against it are at -2. So while in human form (usually an obese person), they might gather flunkies about themselves. In fact, they might have a couple with them even when transformed. The idea of this "person" manipulating the local populace into trusting/liking him and then feeding upon them is pure awesome, IMO.
What a charmer!
Devil Swine are actual lycanthropes. This not only gives them the immunity to non-silver or non-magic weapons, but means they can infect others with the disease. A delightful bit of Mystara trivia: According to some fluff, Orcus –demon immortal lord of undead and lycanthropes– was a devil swine in his mortal form (the first of his kind). This cracks me up, not to mention the delightful tie-ins that might be added to an adventure involving these creatures.
...did I mention there can be FOUR of these things hanging out together?