It's time for the Alphabetical Monster Thing.
Maybe it's just me, but I notice is a faint hint of linguistic family resemblance lurking under the O monsters--O monsters are notable for their otherness. They are more likely to be neutral than evil, but are always decisively separated from humans by some quality suggesting they come from a different world. Odd, other, outside. A word that begins with o is a thing that comes together only after an empty and open moment.
Demons are self-evidently like us--they are us taken to extremes--as are halflings and giants and imps and demon dogs and hellcats and vampires. The "o" monsters suggest the DNA trail is all different--or at least that some point-of-genetic-no-return has been passed. They don't want what we want.
I like the obliviax a lot. It's moss and it eats your memories and turns into you. The best part is the only way to get your memories back is to eat the moss. You can get someone else's memories by eating the moss. This is a great all-purpose plot hook injector especially if you have the kind of players who will put anything in their mouth so long as they found it in a vial.
Pick a color, pick a synonym for goo, pick a weakness, look you've invented a new monster! Green slime, gray ooze, black pudding, I'm sick of it. I'm protesting it. Especially since I just got that Lankmar book and got reminded about how cool Cold Woman is. Now that's an interesting ooze.
Like a lot of the giant ordinary animals, the entry for the giant octopus has a fairly complex set of special rules--in this particular case, for dealing with the octopus' tentacles. (Many of the other animals have systems for what to do if you are swallowed whole.)
I don't automatically think this is a bad thing, at least in principal. If you are a DM with time to prepare, setting different monsters up as if they are their own special minigame can be kind of interesting--especially if taken to an extreme. Each encounter can be just a whole new thing. I mean, that's how combat is presented in novels--each as a unique challenge requiring the hero to completely re-orient him/herself. You have to be fast to avoid the octopus' tentacles, tough to survive the stomach acids of the giant Slorr, wise to see where the displacer beast really is...
In other news, in case you're wondering, according the Manual, the giant squid is in all ways tougher than the giant octopus though the octopus can squirt ink and camouflage itself.
As for the beast itself, I've spent a lot of time looking at octopuses and I feel there's something inherently round and bubbly and feckless about octopi and other cephalopods such that, despite their weirdness and alieness, they often seem sort of innocent (vampyroteuthis infernalis notwithstanding). I feel like I have to give any octopus I use a toothy mouth on each sucker or some other sinister mutation--otherwise the girls are likely to decide to try to tame it and keep it as a pet, mount, or "friend".
Ogres are stupid, ogres are hungry, ogres are lonely. If they are not lonely, then they are in a tribe, and if they are in a tribe the lonely hungry weirdo aspect, which is perhaps the most interesting aspect--falls by the wayside and they just become sort of big bad guys.
So what's the difference between and ogre and a giant--not in D&D terms, but in terms of what you think when you hear them? The giant's hunger and primitiveness seem incidental and perhaps even optional--the giant's theme is bigness and weird scale, giant homes, giant pets--the ogres primitiveness is absolutely essential to its identity--the ogre has to have heads on spikes and giant warthogs for pets and has to be hunched over. (Mandy always imagines ogres as being bigger than giants.) Point is: an ogre is intractable, insatiable, unreformable, irredeemable, uncivilizable, and definitely cannibalistic. A giant isn't necessarily any of those things.
Are ogres unlike us? I think the thing is: we desperately hope they are unlike us. We would like to get away from neanderthality. They make us anxious in a way that monkeys don't. I would let a monkey into my home so much faster than I would one of those wax morons behind the glass in a natural history museum. A monkey is like some cousin you only see at weddings, over in the corner unsuccessfully stacking hors d'oeuvres or knee-deep in cake--they're funny, they've got character, they're harmless. But the ogre? The ogre is like a brother with some tragic, moany, drooly and brutal mental problem. Sitting very close, and very closely related. And we do not want it to be.
Obviously all that about the ogre makes the ogre magi difficult for me to wrap my head around. Basically an ogre mage was D&D's interpretation of an oni before oriental adventures D&D introduced a monster called the oni (like the original monk and the gold dragon were sort of half-assed stabs at Asian ideas that would get fleshed out later) (D&D 4 has just gone ahead and replaced Ogre Mages with Oni).
Anyway the point is, for me anyway, the ogre mage makes no sense with the western connotations of the word ogre. An oni is a big crazy tusked fat thing kind of like a demon but definitely large and physical and with a face like a face on a samurai mask. The magic use is sort of incidental. This is a big, primal creature or spirit that is more made of magic than it is a magic user. Like the plain old ogre it is wild and insatiable, unlike the ogre it is part of a metaphysical web, often tying it to a specific position within a spiritual hierarchy or to a physical place, and almost always to a system of taboos.
Moreover, the ogre is a metaphor for that which is feral and wild within humans whereas the oni is about the inherent wildness and feralness of nature personified in a semi-human form. I have yet to see any version of the ogre mage that seemed like anything other than a marriage of lexical conviennce between these two profoundly different ideas. The ogre is the idea of a human gone wrong and wild, whereas the oni is about things that are perfectly natural in their wildness yet take human form. Or to put it another way, both are feral, but in the ogre the feralness is a failure or falling away, whereas in the oni, the feralness is to be respected as well as feared.
Thanks to Peter Jackson, "orc" is no longer merely a term but actually a word. That is: an idea I can refer to via a verbal designation and expect other people who speak English to know what I'm talking about regardless of what they do on the weekends. The other edge it has over "kobold" (despite that word having a more organic etymology) is that "orc" is actually a pretty good word.
So lets look at that word "orc": J.R.R. Tolkien--who invented the word (in its current usage--thanks comments)--was, against his better judgement, a 20th century writer, and "orc" is--despite his best efforts--a 20th century word. It has less magic in it than "goblin": an orc won't be turning a baby into a loaf of bread or live in a river of liquid spiderwebs. Another thing is: orcs obviously grunt. The word sounds like a grunt. Nothing called orc could possibly not grunt.
This subconscious thread ties the pig-faced orcs so beloved of old school fetishists to Jackson's athletic cannibals. Mundane, greedy, shameless--pigs are a 20th century animal: Orwell knew it, as did Hunter Thompson. Maybe Tolkien knew it, too. Snorting and unenchanted--no wonder they hate elves.
Like I said in the entry for neo-otyugh, this thing is fine if you have a decent mini to go with it. The kind of thing that might spill out of the mouth of a vomiter (maybe named after the noise it makes as it comes out).
The frighteningness of an owl doesn't depend on physical intimidation but on the alien inner world implied by those eyes. "The owls are not what they seem" (Twin Peaks) "It's not an owl" (Paranormal Activity). Making an owl bigger is a little like making Jason in his hockey mask bigger--the wrong trait is being exaggerated.
That said, I like a giant owl much better than a giant eagle, and there's nothing wrong with giant owls as elements of the environment--I just don't want anyone trying to convince me they're extra scary because they're big.
I admit it's fun to say "owlbear" but seriously fuck this monster.