The answer is The converted mana cost of a modal double-faced card is based on the characteristics of the face that's being considered
This deck has so many different ways to draw cards, attack, and even accelerate Energy which is why it is one of the best decks in the format
If you throw in some top-deck manipulation like Sensei's Divining Top and Jace, the Mind Sculptor, constantly recurring fetches also gives you a lot of control over what you draw
Similar to the Mox artifacts, Black Lotus costs zero mana, so you can play it on your first turn along side a land, but adds three mana of any one color when you sacrifice it
Every single card, including the four different pack arts, were graded with PSA and received Gem MT 10 grades