Introducing... Caverns & Chasms!
Most of our community knows of "maby", the development codename for our previous attempt at a cave expansion. Unfortunately, with 1.17 being announced and introducing a lot of our staple planned features like copper, moss, and more, it was canned, with us planning to work on a new cave mod for 1.17.
During our playtesting of our mods, we quickly realized how boring the caves were and just couldn't wait for 1.17... so once again we decided to make a cave expansion mod, this time utilizing some features we already had, combined with new features as well as unimplemented stuff we had planned for mods.
Caverns & Chasms is a full-fledged expansion upon caves. New ores, enemies, foliage, and eventually biomes and structures will all be added to the underground! Let's go through some of the features, shall we?
Deepers
You all know the controversial Creeper changes in Savage & Ravage, right? Well, we're attempting to make them less controversial by trying to keep the destructive element of Creepers still around to an extent. We realized Creeper's explosions are a hassle on the surface, making your land messy or your house ruined, but noticed that explosions underground can lead to a lot of fun, such as revealing ores, caves, or causing gravel to fall. This brings us to the Deeper!
The Deeper is a cave variant of the Creeper, replacing Creeper spawns below a y level of 60 on stone and ore blocks. The Deeper retains the explosive ability of original Creepers. If you still want surface creepers to do explosions, the removal of their explosions can still be disabled, as well as Deeper spawns altogether.

Silver and Gold
Silver is a brand new ore tier, which acts as an alternate to gold. Silver Ore generates in place of Gold Ore in colder biomes, such as taigas, mountains, and tundras. Silver tools apply the Affliction effect upon hitting an undead mob, which damages them when the effect expires. Silver Armor does the same, but to undead mobs when the player is attacked.
Silver has many uses, similar to gold. Silver can be used to make Medium Weighted Pressure Plates, and Silver Buttons when Quark is installed. Spiked Rails are also made out of Silver, which act like powered rails but instead damage entities in minecarts that roll over the rail.
Silver can craft a new trinket called the Ore Detector, which glows when an ore is within a few blocks of the player. The Ore Detector can recieve two treasure enchantments. The first is Treasuring, which limits the ore detector's detecting to treasures only, like diamonds, emeralds, and more. The second is Prospecting, which limits the detecting to metals only, like iron, silver, gold, ancient debris, and more. The method in which what ore is detected may be tuned later, to possibly stray away from enchants.
To compensate for Silver's new abilities, gold has also been tweaked. Golden tools now provide more experience when killing mobs and mining ores. This will hopefully give gold tools some use and viability during the game.
Gold can also be made into a brand new Golden Bucket - a bucket which can hold up to three blocks worth of one fluid at once. This allows for players to carry around much more lava, water, and milk than before.

Necromium
Necromium serves as an alternate to Netherite, like how Silver serves as an alternate to Gold. Ancient Scrap + Silver Ingots will craft Necromium Ingots, just like how Ancient Scrap + Gold Ingots crafts Netherite Ingots. You can smith your Necromium Ingots on to your Diamond tools and gear at the smithing table.
Necromium armor isn't knockback resistant, unlike Netherite. Necromium armor gives weakness to nearby mobs within a range when hit, allowing for crowd control. To balance out, it has a bit less armor toughness. Necromium tools do slightly less damage than netherite, but provide slowness to enemies they hit, allowing to escape from mobs.

Cursed Fire
Cursed Fire is a new fire type. Currently, it only damages undead creatures, but that is subject to change. Rotten Flesh has also been given a storage block, which is one of the main ways to create Cursed Fire. Cursed Lanterns, Torches, and Campfires can also be made in a similar manner as Soul Fire related items, but with Rotten Flesh Blocks instead. Rotten Flesh Blocks also may be given some more use in the future, potentially to help with farming.

Sugilite
Sugilite is a new ore found in Jungle and Desert biomes. Sugilite has its own purple set of blocks, as well as a cool corresponding potion. When a rewind effect expires, it teleport the user back to where they were when they were given the potion effect. This allows for some cool mobility.
Mimes are a deadly new mob found in underground Jungles and Deserts. They seem pretty boring at first, but when they hit you, they will "mime" some of your weapons and gear. Nothing scarier than fighting yourself. When killed, Mimes drop some Sugilite.

Building Blocks
Tons of new building blocks are present, this includes rocky dirt, tiles and bricks for dirt, as well as tiles for cobblestone and mossy cobblestone. Lapis Lazuli has also gotten a few block variants, including a lamps, pillars, and bricks. Sugilite has the same block variants. Several decoration blocks are included as well, such as Golden Bars, Golden Lanterns, and more.

Final Remarks
This is just the tip of the iceberg! There is a lot of unrevealed content, as well as work in progress content. So much more will definitely be coming to Caverns & Chasms, and it will only grow with the release of 1.17! More mobs, ores, blocks, foliage, and even cave biomes will eventually be included in the mod! What you've seen here is currently available as an early beta for supporters on our Patreon or boosters of our Discord server.
