You don't need other Faeries
Every spell you cast this way will replace itself (and hurt you slightly), which means you'll basically never run out of cards if you can keep the Treasure generation coming
Green is a great color identity, so players don't have to be too picky when deciding on a background for him, and the deck's included background, Passionate Archaeologist, is probably the best choice
If your Eye of Nidhogg-enchanted creature is killed in combat (or its hit with some targeted removal), you can thankfully return the aura from the graveyard and back into your hand
Since the original card could be worth a lot in value (or sentimental value) many owners will make a proxy card and use that to preserve the original
But keep in mind that this can easily become the best cantrip when you do have a shuffle effect handy