mtg plains cards Type: Land, Subtype: Mountain, AND, Plains, 11 Plains Set of 3 ⋆

With what I believe is Overkill (translations are divided on this as its not just strict translation, but considering also Final Fantasy translations), we see a removal spell that channels this energy

One of the chasi-est of chase cards in the precons might well be Goldlust Triad, a myriad Dragon that makes treasures on hitting

Lastly, you can see how the framing elements are partnered with Teferi's costuming to extend Teferi from the art into the entirety of the card

My guess is that Amulet of Safekeeping is R&Ds attempt to try and answer the question of how to ensure that Modern players can sideboard against multiple strategies at once so that your progression though a large Modern tournament is less matchup dependent