As the number of cards you can use during a turn is only limited by the amount of mana you have in your pool (compared to the summoning limits of a game like Yu-Gi-Oh!), Black Lotus could allow a player, especially one playing an aggressive Red mana deck, the opportunity to destroy their opponent with zero ability to be countered
Another playable Giant if were looking for a more ramp-based build
Trades are also limited to diamond-rarity and full-art variants from these packs, meaning two-star, immersive, and crown-rarity cards cannot be traded
Which ones we chose was partially based on what could conceivably exist on Kaladesh, but also on trying to find things that some subset of players would be happy with
The only requirement is to play as few basic lands as possible
This will give you flexibility in how you use your tutors, and ensure that you always have a useful target to search for