The Overcast Columns is a biome from the Deeper and Darker mod, and it’s the brown, smoky corner of the Otherside, the dimension behind the portal in an Ancient City. It’s built from 
Gloomslate rather than Sculk Stone, with huge pillars running from the floor to the ceiling and 
Gloomy Sculk spread across the ground.
No mobs spawn here on their own, which makes it the quietest part of the dimension and a good spot for a base. The biome has a couple of things you won’t find anywhere else either, like the 
Gloomy Geysers that throw you high into the air and the 
Crystallized Amber set into the middle of its columns.
Finding It
The Overcast Columns is the warm and dry biome of the Otherside, and the drifting smoke and brown stone make it stand out as soon as you reach the edge of one. Like the rest of the dimension it’s one long cavern with Bedrock above and below, so the columns are the easiest thing to spot from a distance.
The command above will find the nearest one if cheats are turned on. Without them, keep an eye out for brown stone and gray smoke in the air, as no other biome in the Otherside has either of them.
Terrain
The floor is covered in Gloomy Sculk, a black kind of Sculk flecked with orange that you’ll need Silk Touch to collect, and the walls and rock underneath are Gloomslate. Gloomy Grass and the odd 
Gloomy Cactus grow on it, and a few vanilla Fossils are buried in the stone as well.
Further down, where the other biomes have 
Sculk Grime, the Overcast Columns is mostly 
Magma Blocks, 
Soul Sand and 
Soul Soil. It’s worth watching your step down there, as the Magma Blocks will burn you unless you’re sneaking.
Gloomslate Columns
The columns are what give the biome its name, as thick pillars of Gloomslate join the floor to the ceiling all over it. There’s about twice as many of them as there are Sculk Stone columns in the Deeplands, and roughly a third of them are broken in the middle, which leaves a gap you can walk through.
Crystallized Amber
About half of the complete columns have a band of Crystallized Amber in their middle third, which glows a faint orange. Some of those Amber blocks have an item set inside them, like a Diamond, a Gloomsherd or some 
Soul Dust, while others hold a Sculk Leech that’ll come out when you break it.
It’s worth mining these out whenever you pass one, as the items are a decent way to pick up Diamonds and Gloomsherds early on. There’s more on what each block can hold, and how to keep the item with Silk Touch, on the Crystallized Amber page.
Gloomy Geysers
Gloomy Geysers are glowing brown blocks mixed into the patches of Gloomy Sculk on the floor, and they’ll launch anything that steps on them straight up. That includes you, mobs and dropped items, and the push is strong enough to throw you close to 30 blocks into the air if there’s nothing above you.
Coming back down from that height will hurt, so it’s worth having Feather Falling on your boots, a 
Water Bucket to land in, or a ceiling low enough to stop you. You’re able to pick a Geyser up with a Silk Touch hoe, which makes them useful for quick elevators, though you’ll want something soft to land on at the top.
Using 
Bone Meal on Gloomy Sculk spreads a small patch of it around the block, with Gloomy Grass and Cactus on top. Each block in that patch has a small chance to become a Gloomy Geyser, so you’re able to farm a few without needing Silk Touch.
Geysers give off a bit of light as well, and they pop and spit Lava particles every so often, which makes them easy to spot from across the biome. They won’t set you alight though, as the particles are only for show and the block itself is safe to stand next to.
Mobs
Nothing spawns in the Overcast Columns naturally, so the only mobs you’ll meet are ones that wander in from a neighboring biome or come out of a block you’ve broken. The Sculk Leeches sealed inside some of the Amber are the main thing to watch for, as they come out the moment you break the block.
That makes this the best biome for a base in the Otherside, since you won’t have Shattered or Sculk Snappers spawning around it. It’s still worth lighting it up and walling it in, as mobs from the Deeplands or Echoing Forest next door are able to wander over.
Resources
All eight Overworld ores generate in the Gloomslate here, from Coal through to Diamond and Emerald, and they drop the same items as the normal versions. With no mobs spawning around you, it’s the most relaxed place in the Otherside to strip mine, and the Gloomslate itself makes a nice dark building block.
You’ll also be able to stock up on Soul Sand, Soul Soil and Magma Blocks at the bottom of the biome without a trip to the Nether. The full set of Gloomslate building blocks, along with the ores, is covered on the Sculk Stone and Gloomslate page.
FAQ
No mobs spawn in the Overcast Columns on their own, which makes it the safest biome in the Otherside. You’ll still run into Sculk Leeches from inside Crystallized Amber, and mobs from the neighboring biomes are able to wander in, so it’s worth walling off a base.
Break one in the Overcast Columns with a Silk Touch tool, as a hoe is the fastest, and it’ll drop as an item you can place anywhere. Otherwise, using Bone Meal on Gloomy Sculk spreads a new patch that has a small chance of turning a block into a Geyser.
A Gloomy Geyser throws you close to 30 blocks straight up if nothing is in the way, which is easily enough to take a lot of fall damage on the way down. It’s worth having Feather Falling, a Water Bucket or a ceiling above you before stepping on one.
Some Crystallized Amber in the columns holds an item, like a Diamond, an Emerald, Soul Dust or a Gloomsherd, while others hold a Sculk Leech. Breaking it normally lets out whatever is inside, and Silk Touch keeps the item or Leech sealed inside the block so you can carry it away.
