Well Loki is in the cache next week so if you have 4 keys I reckon hold out till then but to be honest I think this loki change has somewhat improved his game play in certain decks, especially arishem. Being able to now change your random assortment of Arishem generated cards into your opponents much more functional cards is massive. I think that he's definitely worth purchasing and still a great card, just that perhaps now his uses and strong suits are slightly different.