Planes of Chaos

 I technically haven't read through the entirety of Planes of Chaos, but I got through the DM guide and moved on to the player's guide, which sometimes has new stuff, but largely retreads the information available to the DM in an abridged manner.

Overall, my feeling is that the Chaotic planes (The Abyss, Arborea, Limbo, Pandemonium, and Ysgard) don't have quite the same "hook" feeling of the Law planes - this might be that, due to their chaotic nature, these planes don't have any real central organizing principle, the way that, for example, Baator (the Nine Hells) are all built around the archdevils and their hierarchy.

I also think that it's here that a lot of actual world mythology comes into play - and while I'm a huge myth buff, I tend to prefer a sort of reimagined, "inspired by" use of that mythology in my fantasy fiction. I'd rather see a new patriarchal god ruling over a pantheon than just come right out and have Zeus show up.

Indeed, Ysgard in particular feels mostly dedicated simply to the Norse pantheon, with only one or two sections that aren't just realms like Muspelheim or Nidavellir. Likewise, Arborea's first layer, Arvandor, is half a feywild-like realm of elves and half just flat-out Mount Olympus (though Olympus, like Yggdrasil, is also presented as one of the interplanar objects that can be used to traverse them - Olympus's lower regions are found in Hades, naturally).

Ysgard, at the very least, has a cool planar structure, like Acheron's cubes or Bytopia's mirrored realms. The plane is made up of earthbergs that float in space, their bottoms (or, in one layer, their tops) covered with molten lava and fire.

Given my preference toward novelty, I found I liked the concept of Pandemonium and Limbo more appealing. Pandemonium exists entirely in tunnels that run through solid rock, with gravity always pointing to the closest wall, and howling winds that leave peoples' minds shattered. Limbo is a soup of ever-shifting elements, and the only way anyone can survive there is by shaping reality around themselves through force of will.

The Abyss is interesting in that it's obviously a terrible place, the home of demons, but in the absence of the ever-present infernal regime found in the Nine Hells, it seems like someone could potentially navigate it with greater ease (though the demons would still come and try to kill you in most cases). Unfortunately, the guide here doesn't describe the Gaping Maw, which is Demogorgon's domain, and apparently during 2nd Edition they had one of the drow pantheon take over Thanatos, which is Orcus' domain.

I think in 5th Edition stuff like Minsc and Boo's Journal of Villainy, Pazuzu's position as the first demon lord and ruler of the 1st layer (the Plain of Infinite Portals - which is a cool location that also works as a kind of hub to get around the Abyss) isn't really mentioned - I think they even give him a different layer under the name of Pazrael. There's none of the lore around Pazuzu being an Obyrith rather than Tanar'ri - I wonder if that distinction came about later, as here I think Tanar'ri is just their term for demons to try to avoid moral guardians from attacking them.

The Planes of Chaos also place the Seelie and Unseelie Courts of the Fey within these planes - the Seelie tend to show up in Arborea while the Queen of Air and Darkness rules in Pandemonium. The Feywild wouldn't be officially introduced until 4th Edition, which is obviously where both Fey courts would show up now.

I'm now moving on to the Planes of Conflict, which I'll write about when I get through the planar descriptions (this one has six, rather than five).