When you are buying, read the rarity symbol and the condition, and confirm the set symbol and collector number match the listing before you trust a "rare" label
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
This attack does 20 damage plus 20 more damage for each heads
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
Cards like Magearna and Adaman might also feature in such a build to ensure maximum synergy
