However, you can consider playing fewer than four copies of a card if: It gets worse in multiples (such as legendary creatures) It's only useful against certain matchups It's a win condition, and your control deck will have time to dig through the deck and find it You're stuck choosing between two cards which have equally strong, similar, but slightly different effects (you could play two of each) It's a slightly worse version of a card you have four copies of already, and you're including it because you want even more of that effect
As an example, the new is a lot less exciting if you already have a playset from
Its possible this particular looter could work in Cheerios, or in an Eggs-like deck, but Ive never seen it given a chance
For the Basic Energies, Lightning Energy was observed the most often (in a smaller sample), which happens to be the Energy which appeared the most times on the Base Set and Base Set 2 Basic Energy sheets
Plenty of decks can churn out a ton of artifacts with enough Treasure tokens to spare some for the activated ability