Ghost Coins
Many kinds of magic withered and died in the 20th Century; Ghost Coins, in contrast, blossomed in power. It’s one of those ‘power in contradiction’ things; it used to be that even when a nation fell apart its coinage would still have some inherent value. After all, a Byzantine gold solidus still had precisely the same amount of gold in it the day after Constantinople finally fell as it did the day before. But with the rise of paper money and coins made out of non-precious metal, well, once the country was gone then so was the value.