They're not on Amazon yet, but Secret Lairs tend to sell out pretty quickly, so good to know they'll also be available elsewhere
Lathril is a wincon on its own, and adding in cards like Shaman of the Pack, Skemfar Shadowsage, and Pact of the Serpent gives Lathril EDH decks a lot of options besides simply turning a ball of elves sideways and smashing face
Eris also has flying and prowess, but the most important thing is: Once it's on the battlefield, whenever you cast your second spell each turn, it creates a 4/4 red Dragon Elemental token with flying and prowess
For returning a permanent, this can be used both offensively and defensively, keeping your important permanents safe or setting the opponent back on mana by making them cast it again
For $100,000, You Can Have the Most Valuable Pokemon Card Ever This is by far the most anyone has asked for a trading card like this Once, Pokemon was all the rage
All of these cards are considered part of the Standard format and are legal for play in events that take place using the Standard format