Return any number of cards with total mana value X or less from your graveyard to your hand, where X is the total of those results
Exert characters to quest for Lore or challenge their opponents exerted Characters
The Plot mechanic alluded to on the card Fblthp, Lost on the Range works like foretell, but you cast plotted cards without paying their mana costs at a later turn rather than for an alternative cost
Again, instant and sorcery cards don't count
So while "Don't worry, players will still be able to use all their cards" is true, it's true in the weird, rules-lawyery sense of the term where you name Borborygmos with your Pithing Needle only for your opponent to say, "Gotcha, I played Borborygmos Enraged, not Borborygmos." The community was hopeful that Historicthe non-rotating format designed to keep cards playable after rotationwould be " Arena Modern." Many actually expected it to cross over into paper play and become a post-Modern non-rotating option