This is a continuation of this post. So if you haven’t read it, go do so before reading this one.
One commenter on this post asked why there’s no Nth metal artifacts from Legends season 4. At the time, I said I couldn’t really think of anything. But I just got an idea.
Instead of something specific from that season, the Nth metal artifact is a large collection of the stuff locked in a vault in Hell. A the vault is hidden away in a secure part of Hell whose location is known by only one man, Lucifer Morningstar. So, one of the plots can involve Constantine and Astra going on a Sojourn through Hell to find Lucifer’s Nth metal cache. And as for allies they can recruit on the way, Astra still has Vandal Savage’s soul coin, so he might be useful. Or maybe Lucifer can send Mazikeen down with them as a guide.