"Unlock Rare Resources in LEGO Fortnite: Blast Core, Metal Smelter, Brightcore, Copper Bars, and Cursed Bone"

LEGO Fortnite players can obtain the Blast Core by entering a Lava Cave in the desert biome and eliminating a Blaster mob, which drops the item. Players should be cautious as the Blaster mobs can explode if not eliminated in time. Ranged weapons or quick close combat attacks are recommended, and players should be prepared with charms and food items to prevent burning. The Blast Core is necessary for creating a Metal Smelter in the game.