The big challenge in exploring Dark Box is not knowing if the deck is able to beat Shadow Rider Calyrex VMAX, but learning and building a list capable of winning several other matchups without spoiling the positive matchup that the deck already has against Shadow Rider Calyrex VMAX
However, what we can do is look at heavily played Standard cards, and see when (or even if) their impending rotation caused people to sell on a card
Slith Firewalker Creature Slith Haste Whenever this creature deals combat damage to a player, put a +1/+1 counter on it
I keep anything and everything
ANY BODY WILL DO In my experience, the logic of Commander deckbuilding evaluates cards for their rules text much more than their card type
Rarity: M #: 19 Card Type: Legendary Artifact Flavor: On loan from a private collection, this unique mechanism extracts power from a carefully prepared gemstone