Sometimes, I have ideas. Here are some below. I might work more on one of them if you think they are interesting.
Which do you think are interesting?
1. Runefist Monks: An ancient order of dwarven monks who practice a unique form of runesmithing, which allows them to channel the physical properties of substances into their bodies. They have three schools, Elements, Alloys, and Ceramics, and practitioners of these schools are able to make their bodies take on qualities of their respective substances. For example, an Element user can use [Copper Body: Skin] to allow themselves to conduct electricity, or a Ceramic users can use [Diamond Touch: Piercing Strike] to make their finger as hard as diamond. Probably involves flesh runes, and a Paarthurnax-style leader. New elements are created by punching each other really hard.
2. Dwarven Drill City: A colossal steam-powered drill a few miles underneath the world, populated mostly by dwarves, which has survived for a few thousand years. They send up smaller drill-pods full of dwarves armed with assorted digging instruments to raid the surface. Goblinkin are enslaved by them to work in the drill's boiler rooms. Their religion is all about spinning things; the more revolutions something has made, the more holy it is.
3. Molten King: A dwarven city built into a volcano, ruled by a mysterious figure called the Molten King. Clad in a suit of constantly-deteriorating armor, the Molten King claims to be a spark from Yemekar's forge. He is incredibly hot (hence the armor's persistent melting), and requires regular repairs by his blacksmiths to prevent himself from crumbling apart. He sits on a huge slag throne in a council chamber suspended above the center of the volcano. Primarily, he is focused on the reconquest of the deep roads, and seeking even deeper paths into the earth.
4. Broken Yemekar: A cult which found a massive golem core, spoken of as the Heart of Yemekar. They also possess a powerful rune called Yemekar's Flesh, which converts living creatures to clockwork when it is inscribed upon them. They are constantly on the lookout for mechanical artifacts, as they believe that when Yemekar shattered to create the universe, pieces of him were thrown into the imaginations of dwarves throughout all time, allowing them to eventually rebuild and reconstruct him. This is, in fact, vital: Yemekar was only present in the past because the dwarves built him some time in the future, at which point he will transport himself back in time to the dawn of creation to forge the universe.
5. Not-a-Forest: A weird forest made of stone, crystal, and other non-living elements. It even has stone-and-earth animals, like basalt bunnies and limestone lynxes. It arose from an attempt to replicate the creation of a Word Altar by a collection of powerful dwarven runesmiths; their creation converted everything around it into stonework. By the way, it also has rock people.
6. Microdruids: A collection of druids who use kuria lenses in order to commune with microbes and other small creatures. Experts at managing disease outbreaks. Smarter than your average druid. They don't follow lab protocol, but they can also just politely ask every other organism to shoo.
7. Crystal Druids: A collection of druids who commune with rocks, but only the living kinds of rocks. Amethyst, halite, calcite, for instance -- all of these rocks live and change, and even adapt their molecular structure when they come into contact with contaminants. All it takes is a salty brine to foster their growth. Disorganized stones, like the kind commonly found, are much less sentient, and therefore hardly ever reply to even the most fervent communion.
8. Monastery Fortress: A strange fortress in Aeldin populated by an ancient Canonist order which has been holding back the tide of barbaric greenskins for thousands of years. It is one of the only places where salt paladins are made, these being men and women who gradually desiccate themselves until they are husks of people, animated by a ferocious will and belief in GOD. Underneath the monastery is a massive network of boarded-off tunnels, full of strange creatures, hidden chambers, and relics of the faith.
9. Mercantile Lichdom: If you could grant immortality to people, wouldn't you sell it? That's what some liches do. They have big ships staffed by crews of the undead, and operate vast trading networks across oceans. Who needs the right of primogeniture to preserve your wealth when you can just do it yourself? These undead are phenomenally rich. They’re the Warren Buffets of medieval times. They don't really care for wanton murder or destruction. They do, however, have very tightly binding contracts. A living man who signs a three-year term on one of their vessels will be resurrected as an undead to finish that term, should he perish beforehand.
10. High Elven Inbreeding: A the-hills-have-eyes style setup where high elven purity goes too far. Many deformed elves. Some are hypermagical, but most are just horribly malformed with significant breathing difficulty. They want to eat you.
11. Ghost Aristocracies: If a ghost truly is a continuation of a person, then all their material wealth should continue to be owned by that ghost. After shuffling off the mortal coil, usually by the consequence of disease or accident, the fabulously wealthy (and often quite politically powerful) might continue to linger on as a ghost. In this, they can live quite well: going to concerts, having professional food-tasters describe food to them, and gawking at paintings. Some still manage their affairs, by ordering around servants to do particular things. Surprisingly, only a minority are interested in returning to life. Entire kingdoms have had their upper class replaced by ghosts.
12. Summoned God: A few hundred high elven sorcerers come together and bish-bash-boosh, summon some magical creature with their collective power that will act as their controllable god. It works for hundreds of years, until a rather unfortunate truth settles upon them, that being their own mortality. As they perish, the Summoned God grows steadily more free. The remaining mages are desperate to preserve their own lives, to prevent the Summoned God's release.
13. The Land of Trunks: Long ago, a collection of blood mages conducted a ritual using what was 'a drop of the blood of god', or so they say. They wanted to bring about the end of the world, but a cabal of dragons and sorcerers erected a powerful system of barriers to prevent this. The result was that an eight-kilometer area of the apocalypse was generated around the castle that was the blood mages' base of operations. Within, the end times have arrived: Ramakhet devours the world, Khorvad has legions of golems/evil dwarves/undead, and Iblees is seeping up from the earth. The catch is they're also all fighting each other.
14. The Stink-King: A goblin shaman who has mastery of smells. He has a horde. He can summon smellementals. He has olfactories which produce scent-based weapons. His greatest nemesis is springtime allergies.
15. October King: [???]