How do you unlock the blast furnace and what does it allow you to smelt?

The blast furnace is a crucial late-game crafting station in Valheim, allowing players to smelt advanced metals like black metal and flametal. To unlock the blast furnace, you must first defeat Moder, the fourth boss located in the Mountain biome. Moder drops Dragon Tears, a key ingredient required to craft the Artisan Table, which is necessary for building the blast furnace.\n\nTo begin, you need to locate Moder''s summoning altar in the Mountains. This requires exploring the biome and finding a Vegvisir stone, which reveals the boss''s location. Once you locate the altar, you must gather three Dragon Eggs to summon Moder. These eggs are heavy and require careful planning to transport, as they cannot be teleported. Use a cart or a longship to carry them to the altar.\n\nAfter defeating Moder, you will receive Dragon Tears. These are used to craft the Artisan Table at a level 5 Forge. The Artisan Table unlocks advanced crafting recipes, including the blast furnace. To build the blast furnace, you will need 20 fine wood, 10 iron, 5 surtling cores, and 5 chains. Fine wood can be obtained from birch or oak trees in the Meadows or Plains, while iron is mined from muddy scrap piles in the Swamp biome. Surtling cores are found in Burial Chambers or dropped by Surtlings in the Ashlands, and chains are obtained by defeating Wraiths in the Swamp or looting chests in dungeons.\n\nOnce the blast furnace is built, it allows you to smelt black metal scrap and flametal ore. Black metal scrap is dropped by Fulings in the Plains biome, while flametal ore is found in the Ashlands. These materials are essential for crafting high-tier weapons, armor, and tools. The blast furnace operates similarly to the regular furnace but has a larger capacity and faster smelting speed, making it ideal for processing large quantities of ore.\n\nA common challenge players face is gathering enough chains to build the blast furnace. Wraiths are rare enemies, so farming them can be time-consuming. To increase your chances, explore Swamp crypts thoroughly and use a bow to safely defeat Wraiths from a distance. Alternatively, you can find chains in chests within Sunken Crypts or by defeating Stone Golems in the Mountains.\n\nAnother tip is to set up your blast furnace near a Forge and other crafting stations to streamline your workflow. This minimizes the time spent running between stations and allows you to craft advanced gear more efficiently. Additionally, consider building a portal network to transport resources quickly between biomes, especially when gathering materials like fine wood or iron.\n\nIn summary, unlocking the blast furnace requires defeating Moder, crafting the Artisan Table, and gathering specific resources. Once built, it significantly enhances your ability to smelt advanced metals, paving the way for endgame gear. By planning your resource gathering and optimizing your base layout, you can maximize the efficiency of your blast furnace and dominate the challenges of Valheim''s late game.