Once he felt that he had a suitable selection of cards, he created a hand-drawn 120 card deck, known as the Alpha playtest cards
When you crack open each Secrets of Strixhaven Collector Booster, youll get Rares and/or Mythics, Traditional Foils, a Full-Art basic land, and Mystical Archive spell cards

Consider everything she facilitates: Freedom of play on your turn An ungodly amount of creature and artifact enter-the-battlefield triggers (and, likely, leave-the-battlefield triggers) An equally ungodly number of bodies to send to battle or sacrifice to the altar of your choice or tap to pay for convoke costs (consider that Throne of the God Pharaoh regularly loses opponents 10+ life at each of my end steps, if it doesnt just end the game) Offense and defense, as this deck can send everything it has every single turn, with Myrel creating untapped replacements for every single soldier you have Ample low-mana value, low power/toughness creatures to trigger all of whites card draw effects If a commander were printed that read: protect your board and make an army, such a commander would be considered a playtest card for White: the Commander
There are all sorts of permutations of cubes, from high-powered to rarity-restricted, special rules to color-restricted, and many, many more flavors