NFC Tags, I bought NFC Amiibo cards on Ebay for 16.00 USD, and it came with 22 cards and they ALL WORK, even since they are not made by Nintendo and from china.
I am happy with my purchase, I have two eponas, a WW boomerang, trousers of time, tunic of the winds etc.
And my Wolf Link Card appears with 20 hearts. 
I've heard of this cards for a while. Since they are not by Nintendo, I have kept my distance. In saying that, I think they are a neat idea. Considering Nintendo dealt the Animal Crossing cards, it would have been nice to have an option to get the rest in this format. Not everybody wants the clutter of the characters and by themselves, they could even entice collectors paying twice for having the favourite characters in both formats.
I am happy with the figurine collection so I am okay buying Amiibos. The only one I really wish I had and I haven't gotten around buying is Ganondorf.
