akkamaddi's Simple Cthon

Cthon is a very rare, tainted, toxic ore found in the Nether. It is comparable to Dragonstone, but more rare, and more difficult to prepare.

When the ore is found, it requires a pickaxe rated level 4 or higher to successfully mine. Diamond will not mine Cthon. At this point, the materials that will successfully mine Cthon are Onyx (Simple Ores), Dragonstone (Netherrocks, presuming GitHub matches the download), Scarlatite Gold and Hephaestan Gold (Golden Glitter), Green Celadon (Simple Cobalt), Black Silver (Sterling & Black), Tenebrium (Simple Arsenic, and Old Lace), Prasinos (Simple Tungsten), and, of course, Cthon.

Cthon ore drops one, and only one, Mephitic Cthon Chunk. Due to its innate resistance to magic, the Fortune enchantment does not work on Cthon ore. The Mephitic Cthon Chunk is too caustic and toxic to be used directly. It must be purified, and what purifies it is something simple that is not found in the Nether. It must be fused with a block of ice. Cthon is also highly reactive with Gold, and so a Gold Nugget is the catalyst to refine a Mephitic Cthon Chunk into an Elutriated Cthon Chunk.

The Elutriated Cthon Chunk can then be smelted in a normal furnace to produce a Cthon ingot. The Cthon ingot can be used to craft armor and a complete basic tool set, using standard recipes. (The tool recipes should be compatible with most mods that add wood.)

If a full suit of Cthon armor is worn, its innate resistance to magic gives it a very special function. The complete set prevents the Wither status from doing damage. The Wither status will still take effect, causing weakness, but it will not cause a loss of health.