Biomes
Magma Biome [Overworld - Man, that's a weird name. Name the world, pls Klei.]
Geysers and Magma Piles, like in SW. However, it's more likely for geysers to not have rocks on at worldgen.
3 days after being dug up, it's at the worst stage of rocks, 5, it's medium, 7 it's back to normal. 14 and it "explodes", destroying the rocks and leaving nothing.
In Meteor Showers, Dragoon Eggs will rain here instead, leaving small lava pools that eventually turn to Obsidian (which is mineable in DST, as it would need to be.) + 20% chance for a Dragoon in addition | or | (20% chance) occasionally survive. After 3 days, it "drops" a nest into the Lava Biome (canonically, it's right under the Magma biome.) - effectively just gives renewable Dragoons.
Hot Lava cameo(?) - perhaps sometimes the geysers could shoot up small things such as Chairs and Bedside tables. These would come back down and shatter on the ground, turning into 1 or 2 boards.
Useful for: Gold, Rocks, Obsidian, Dragoon Heart, Boards(?)
Lava Biome [Caves]
Effectively a smaller volcano in the caves, it houses Dragoon Nests, Coffee Plants, Elephant Cactus, Obsidian Boulders, and the turf to match.
Every now and then, the lava will "explode" directly upwards. This can be examined by the player.
Wickerbottom - "Not even I can explain this phenomenon of science.", for example.
Hot Lava cameo - Every now and then, charred furniture will "float" in the lava. Perhaps it should be examinable. These would be things like dressers and coffee tables modelled after furniture in Hot Lava.
Useful for: Coffee, Elephant Cactus, Obsidian, Dragoon Heart
Tweaks
Dragoon Heart - Gives fire resistance for one minute. Can be cooked into "Sweet and Sour Turkey" or "Dragoon Blood"
New Items
Veiled Heart - Much lighter in colour than a Dragoon Heart, it can revive a person at no cost to Max Health. However, at 40% hunger and 80% sanity. - Dragoon Heart, Nightmare Fuel x2, Ashes x4
Ethereal Pearl - Resembling Yin and Yang without the circles in the sides. It can be crafted in turn to an Umbral Amulet - Veiled Heart, Shadow Atrium
Umbral Amulet - A 5 use "revival" amulet. Each revive costs 20% of it's durability with the perks of a Veiled Heart. Can be haunted (which won't equip it) or handed to a ghost (which will equip it) - Restores Sanity at the cost of Health. +3 sanity, -2 Health every 2 seconds. Can be combined with Jellybeans for a quick Sanity restoration. Lasts 3 minutes in this use, losing 1.1(recurring) percent every 2 seconds.
Sweet and Sour Turkey - Same stats as Bacon and Eggs, but gives you resistance to cold and heat (120 insulation) for 2 minutes - 2x Turkey Leg/Drumstick, 1x Dragoon Heart, 1x Vegetable
Dragoon Blood - A vial of flavoured coffee with a jelly consistency, gives fire resistance for 4 minutes. - Royal Jelly x1, Dragoon Blood x1, Coffee x1, Filler (anything)
Now if anyone would just read the post instead of brigading *cough @Ecu cough* the world would be a better place, no?