These are the cards that are good in multiple decks, allowing you to have the most flexibility when deck building
The Tempest Medallion Cycle The Medallion cycle cards from Tempest are most often seen in mono-colored decks, but a high enough concentration of gold cards can make them worthwhile in decks with two, maybe even three colors
I suspect the absence of a guaranteed rare in Value boosters is, in part, specifically supposed to deter collectors, so that these boosters stay in stock for kids to buy
And in the worst case scenario, you could grab an opposing blocker and turn it into your attacker so your forces could come in for the win
Examples are Battle of Wits (which requires a huge library to win the game) and Scapeshift (which requires playing enough Mountains to one-shot your opponent with Valakut triggers)
If a card is not on the Reserved List, there is always a chance it could be reprinted