If a card costs 6 mana, it basically has to say you win the game, and while Dream Eater does a lot of stuff, it honestly doesnt give you any card advantage just tempo, which is a problem for something thats 6 mana
Dominating the aerial battlefield is always a concern in MTG matches, and this deck takes advantage of it
This record sale suggests collectors are no longer treating it like a warm-up act
However, consider copyright
Note that once exiled, they cannot be cast from the graveyards, so this is a break on things like flashback or retrace
Better still, it also gives all instant and sorcery spells in your hand Affinity for creatures, too, making it a highly playable card in Standard, Limited, and Commander.