This pdf is 26 pages long, 1 page front cover, 1 page advertisement, 2 pages editorial, 1 page ToC, 1 page information for novice DMs on how to read statblocks, 1 page SRD and 1 page back cover, leaving a total of 18 pages of content for the latest installment of Raging Swan's TRIBE-line, so let's check out these dour dwarves!
The Duergar of the Obsidian Citadel (which btw. comes with environmental information/a city statblock) live in a subterranean fortress built into volcanic caves, toiling away at unfulfilling lives, creating masterfully crafted item upon masterfully crafted item - but with a twist: While they are masters of all kinds of craftsmanship, the grey dwarves also seek to experience true beauty and thus raid the world for charismatic beings - in fact, there's a whole section that provides guidelines for slavery/ paying for items in beautiful beings.
If you've been following the whole TRIBES-series, you'll know that one can expect some TRIBE-specific rules and this is no different: We get a Sunder Specialist alternate type for the Fighter, 3 rogue talents helping with the duergar's natural invisibility and stalking capabilities and two focused schools for wizarrds, the armour and weapon schools. The former can grant you minor DR and add properties to you magic shield, where the second grants access to an energy burst and force weapons. Tribal warfare also gets its due with 7 new feats, many of which are exclusively available to duergar of the obsidian citadel: From extended enlarge-abilities and invisibility to 3 feats that add effects after successful sunder-attempts to a new two-handed weapon defense feat that actually makes for a rather interesting style of combat. The 6 new spells range from reskins/minor modifications of other spells (Obsidian shards deals 1d6 per level damage up to a maximum of 10d6 as a third level spell- in a cone) to a spell that is titled "Greed", but makes the target essentially view anything valuable as worthless. My favorite spell curses an armor and takes away some of its protective capabilities.
But the truly central ability and quite possibly the one that will make the PCs LOATHE the duergar is their ability to place circumstantial and/or delayed curses on their items: Not only is a feat designed to reflect this capability, but there is actually a whole page devoted to different types of curses for different item catgeories to provide you with sample smatterings if your PC has failed to grovel sufficiently at the feet of the duergar - for there's also rules to properly reflect how hard it is not to offend the dread masters of the obsidian citadel. Another favorite passage of mine! It should also be noted that 5 different new magic items, from special goggles to a constricting net and a vest that may grapple foes are provided alongside two simple monster templates to reflect constructs made of silver and gold.
And then there are the statblocks. Thankfully, each statblock comes with a version of the statblock to reflect the enlarged version of the respective grey dwarves. We get stats for regular warriors, scouts, captains (including silver horses), a statblock of a sunder specialist, one for the wizards and one for in infiltrators and even one for a golden dire boar.
The true stars of this installment, though, are the fully developed NPCs, each taking up 2 pages and coming with their own, neat b/w-artwork and a most expansive Raging Swan-NPC-treatment, i.e. fully-developed backgrounds: Reigal is an oddball among the duergar: Not only is ha chaotic and belongs to the royalty, he's also a rogue 3/Sorceror (fey)3/arcane trickster 7 - quite cool and one of my favorite characters to come out of the TRIBES-line. The second is the citadel's finest weaponsmith, paranoid and xenophobic Kavar Teethgrinder (a more straightforward expert2 /wizard 11).
Editing and formatting are top-notch, I didn't notice any glitches. Layout adheres to a 2-column b/w-standard and the pieces of b/w-artwork rank among the most gorgeous yet seen in a TRIBES-supplement. The pdfs come with a printer-friendly version as well as a pdf of collated statblocks for your Raging Swan-NPC-statblock library, still one of my favorite innovations by RSP. The pdfs come with extensive bookmarks. At first, I admit to being slightly disappointed in the duergar of the obsidian citadel - when directly compared to the iconicity of the "Orcs of Eternal Zenith" or the "Bugbears of Frozen Tears", the dour duergar feel a bit bland. But that feeling thankfully left me rather quick - with the great twist of them being as fine smiths as they are, their craving for beauty and art and especially with the stellar ideas regarding the interactions with the dwarves and their delayed curses turned the whole pdf around. The curses provided and the interaction guidelines more than make up for the spells and feats, which are "only" ok, but nothing to write home about. Add to that the NPCs with their extensive write-ups and we're in for a quite neat total package. If the line hadn't put the bar as high as it has, I'd go all out on this one, but since the last installments were as mind-boggling awesome as they were, I'll "only" settle for a final verdict of 5 stars, but sans seal of approval, as I think they could have been even better with even more iconic metal steeds or e.g. a sample slave auction or a more developed reason for their craving of beauty.