You can sacrifice Ertai in a pinch, though
Because of the incredible illustrations, they are wanted by many collectors across the globe
The 1-Star rare limit also means that while you'll be able to trade rare full-art cards, like Bulbasaur (A1 227/226) or Marshadow (A1a 074/068), you'll be blocked from trading harder-to-find cards like the 3-Star Pikachu ex (A1 281/226) or the Golden Crown-rare Charizard ex (A1 284/226)
The Foundations set on the whole has stood out to me for several reasons: 1) Beginner Products As I understand it, a set similar to the Foundations set tends to come out every 5ish years or so, typically to allow a guided pathway into MtG for newer/returning players
Personally, I think Kenessos will end up becoming the de-facto commander for the tribe as far as optimal builds go, but I think Arixmethes will be more popular because its just a huge monster
Yawgmoth's Will ($245) Not only is Yawgmoth's Will a Reserved List card, but its also still a very competitive one