Personally, I think the carbuncle is trying to be two different monsters at once. On the one hand, it is a puzzle to get at the super valuable gemstone in its head, since the jewel will crumble to dust unless removed properly (using charm spells and the like). On the other hand, the carbuncle is also a mischievous creature that actively tries to sow discord within the adventuring party using its telepathy and empathy. These are two very different challenges to the players, and in a way I feel like the carbuncle's need to cover both of those bases ends up weakening it conceptually. I do really like that it just able to will itself to die though, thats a very interesting touch, and I think it looks absolutely adorable.
Honestly the caryatid column is just a much more interesting golem than the actual original stone golem. Them using built-in swords is an incredible touch, that really feels different from the brutish vibe that golems and other constructs normally have... they feel almost agile and purposeful with violence. This vibe is furthered by how the caryatid column only ever acts in defense, or if someone commits an act that they have been tasked with prohibiting. It is a much more interesting construct than the golems are honestly, and it being a particular ancient architectural feature is really fun. I would definitely use these, they feel just right for King of Kings.
The name is great, and I think the caterwaul has some great ideas. The randomly generated AC bonus and attacks per round is an interesting idea, but I don't think it is executed very well. I wish the table was just more uh flavorful or evocative, rather than just steadily increasing bonuses. The screech is a nice touch, which makes a lot of sense since caterwauling literally means screeching, though usually it means screeching like a cat in heat so does that mean that the caterwaul is horny 24/7? I think I would just use a normal big cat here.
I said before that I love bugs in games, and the CIFAL (capitalizing every letter because its an acronym and I just think thats fun) is a very fun bug creature. I actually one time had a hive of colonial insects as a playable character race-class in a bug-oriented game I ran, there was an NPC in that game that was that race and was a walking talking paper wasp nest where the nest paper itself formed their skin. To say the least, I really like the concept of a humanoid agglomeration of arthropods. The thing where the CIFAL only has 2 real hit dice but has 8 hit dice to draw from to regenerate as they take damage is really interesting mechanically, and incentivizes really big hard-hitting attacks if you do get into combat with it, but I feel like if combat doesn't come up then its a bit of a waste. Honestly this would be a 5 star monster if it was done a bit better or with a bit more specificity.
Honestly I am much more likely to use a real world large flightless bird instead of a clubnek (or an axebeak for that matter). The clubnek is even explicitly a mutated ostrich. Just use an ostrich/emu/moa/cassowary.
Now I know I said before that I wasn't into having so many variations on really simple undead monsters, but I just really like the coffer corpse. Funeral barges are generally really cool, and I actually quite like how the coffer corpse uses really quite mundane mechanics to make it feel pretty distinct from other undead. They appear to take damage and collapse if they take too much but in reality are unharmed, and a successful hit results in the coffer corpse strangling the target. Honestly, I think if this were a default undead instead of a normal zombie, it would be incredible. I might just use the "appear to take damage but really they're fine" thing for just about all undead now.
The coffer corpse was first printed in the Fiend Factory column, with this just absolutely incredible illustration that focuses much more on the boat than on the actual corpse inside of it! Mechanically, the Factory coffer corpse is identical to the Folio one, although the mention of a fear effect is different: the Factory corpse only causes fear in NPCs while the Folio corpse causes fear for anyone engaged in melee with it.
Personally, I think the coffer corpse is an incredible and very iconic yet very simple undead creature. Since they feature on funeral barges, I would readily use these as random encounters along a river, perhaps tied into a common funerary practice for notables in a society. Imagine running into a clump of funerary barges on the open sea, all filled with the unquiet dead. Maybe the coffer corpse could do with more focus on the boat even! As it stands, the coffer corpse is a very usable and very fun undead monster, and both illustrations of it are fantastic.
yesyesyesyesyes I LOVE crabmen, of all sorts. Crustaceoids, just like insectoids, frequently feature in my games, and the iconic rather goofy-looking Fiend Folio crabman is a fantastic addition. Sure they look basically nothing like crabs, but personally I think that that is a-okay. They remind me a lot of 1950s creature feature monster movies. I couldn't find a large enough picture of it online, but on the page facing this one there is a drawing of a fight scene where one of the crabmen is carrying off a woman over its shoulder, just like similar scenes from alien invasion and monster movies of the 1950s and 60s, which are some of my favorite movies ever (though of course I am not very enthused by the sexist and racist tropes that ooze throughout such works, as reflected by that very image of a crabman carrying off a woman). The FF crabman is mostly just a normal humanoid enemy, but it is a very flavorful and fun one! The note about them hoarding silver is interesting, because I think it provides for potentially interesting dealings between the players and the crabmen. Trading silver spoons for passage through a partially flooded section of cavern perhaps.
Not an especially necessary undead creature, and I think it could easily just be handled as some kind of wizard skeleton rather than its own distinct thing. I honestly do kinda like how much of an asshole it is without actually killing or hurting the players in any real way. Teleporting some of the party away and claiming that they are now dead, or paralyzing them and turning them invisible simultaneously (which is mentioned as a variant in the description) is just so mean but in almost a playful way. I honestly appreciate that. I just don't think it needed to be a completely different creature from other undead.
Next up are the D monsters, of which there are a lot, so I'm looking forward to that! See you all soon, and I hope you have a lovely happy new year!