Since the printing of the truly colorless Eldrazi in OGW, they have become very important to run Eldrazi decks that play multiple colors, such as Bant Eldrazi
Your graveyard is a resource much like your mana or life total, so if you can play efficient cards that let you pull or replay cards in your graveyard, Gambles downside is irrelevant during those unlucky moments where you discard what you searched for, as all youve done is turn your Demonic Tutor into Entomb
Psychomancer is a wincon, allowing you to kill people with your sacrifice and recursion engines, while Sautekh Immortal can come in as a huge body after you have your engine running
The Ring Card // The Ring Tempts You Card is a Emblem card in Magic: the Gathering MTG
Both of these cards/categories are incredibly strong
From a financial perspective it is a useful exercise to try to forecast which cards might be included in this set so that you can decide what you might need to do about it