Terraria is full of unusual crafting materials and Rotten Chunk happens to be one of them. It is literally a rotten chunk that is used in crafting a variety of items and even summoning some bosses.
Rotten Chunk, very much like the name suggests, cannot be eaten. It can only be used for preparing Worm Food, some wearables, crafting the Mechanical Worm, and more.
Terraria: How to Get and Use a Rotten Chunk
A Rotten Chunk is a drop from Eater of Souls, Devourer, and Corruptor. You cannot craft the chunk or find it in chests. You will have to slay these enemies to get the chunk.
Once you get your hands on some Rotten Chunks, it’s time to craft some not-so-tasty-looking stuff. The most straightforward item that you can make with 5 Rotten Chunks is Leather. Head over to the Work Bench to combine the chunks and get leather.
You can make the Timeless Traveller’s Footwear and Cloak by putting together Rotten Chunks, Black Dye, and Silk. You will need to find a Loom to combine the ingredients.
To make a Coffin Minecart, you need 10 Rotten Chunks, 10 Wood, and 5 Iron Bars of any kind. You can put these items together Iron or Lead Anvil.
In the Crimson World, you need to use Worm Food to summon Eater of Worlds. To make Worm Food, you need 30 Vile Powder and 10 Rotten Chunks.
To summon the Destroyer, you need to create the Mechanical Worm. For this, you need 6 Rotten Chunks, 5 Iron Bars of any kind, and 6 Souls of Night. Now you need to find a Mythril or Orichalcum Anvil to get a Mechanical Worm.
Lastly, the Rotten Chunk is used to brew the Battle Potion along with Deathweed and Bottled Water.
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