akkamaddi's Arsenic and Lace - Updated Version for Modern Builds
This project represents an adaptation for Minecraft versions 1.16.5 and later of the original Arsenic and Lace module from the akkamaddi's Additions mod created for version 1.7.10. The initial development belonged to akkamaddi, but after support was discontinued, the project was taken over for maintenance by other developers.
The mod introduces several new materials to the game: arsenic, arsenide bronze, and arsenide gold, as well as antique lace burial shrouds. A distinctive feature is that arsenic is not mined as ore but is entirely produced in the Fusion Furnace. Starting from version 1.18.1, rare arsenic ore and the Tenebrium material have been added.
Historically, arsenic salts were used to preserve taxidermy exhibits. In the Minecraft world, dark forces use these same substances to preserve zombies! Using the magic of the Fusion Furnace, you can combine rotten zombie flesh with skeleton bones or slime balls to obtain the minerals orpiment and realgar. This initiates a chain of processes to create purified arsenic ingots.
Arsenic can be used to create tools, but due to the metal's brittleness, armor cannot be made from it. When alloyed with copper, arsenide bronze is produced, and with gold, arsenide gold is created. Both alloys are strong enough for making both tools and armor. Additionally, from arsenide gold and obsidian blocks, the glass-like material Tenebrium is created, distinguished by exceptional durability.
Sometimes during arsenic extraction, ancient lace shrouds in which the deceased were buried are discovered.

Tool and Armor Characteristics
Tools made from pure arsenic are similar in characteristics to wooden ones but have slightly greater durability and improved enchantability. They are repaired with arsenic ingots.
Arsenide bronze creates tools comparable to regular bronze but with increased durability and enchantability. However, they are less sharp and work slower than standard bronze tools. Repair is done with arsenide bronze ingots.
Tools made from arsenide gold are similar to golden ones but with lower enchantability and greater durability. For repair, arsenide gold ingots are used.
Tenebrium in most parameters falls between diamond and onyx but possesses exceptionally high durability.

Necrotic Furnace
In Minecraft version 1.18.1, rare arsenic ore and the grim Necrotic Furnace have been added to the world. As conceived by the author:
"The Necrotic Furnace is a regular furnace with an additional output in the lower corner. It runs on necromantic energy. Rotten flesh and bones smelt eight items, and bone meal smelts one item. (A Shroud can fuel the furnace for 64 smeltings, and bone blocks for 80 smeltings. The heads of undead monsters can also serve as fuel.) Each smelting has a 25% chance (configurable) to create Toxic Soot in the additional output. Toxic Soot items can be combined into a Toxic Lump, which is then smelted into an Arsenic Nugget. This allows players with large stores of zombie flesh to use it as useful fuel while obtaining a small amount of arsenic for alloys. Moreover, cooking food in an arsenic furnace using zombie flesh that releases necromantic energy gives it a delightful roasted almond flavor and is excellent for weight loss diets as your fingers and toes fall off."

Cooking meat in the Necrotic Furnace turns it into rotten flesh, and cooking potatoes (or other configurable vegetables) turns them into poisonous potatoes. If you or the modpack creator believe that the ability to infinitely produce fuel by cooking meat in the Necrotic Furnace is too advantageous, this feature can be disabled in the configuration file.