Talk:Night's Edge/@comment-96.51.148.84-20130218201955/@comment-4674838-20130219234654

Every world has demon altars, usually you can find several of them in the underground corruption. The only exception to this is if someone has smashed the demon altars with a Pwnhammer (to get the hardmode ores), in which case you'd need to make a new world and find a demon altar to craft with.

i.e. make a new world or look harder in the underground corruption. They're there.