I'm going to call the different parts that need to be found in the booster pack as elements. The different elements include:
- Mechanic 1, 2, 3, ...N
- Non-Mechanical Theme 1 ...N (Eg. Scars of Mirrodin's "familiar-feeling"/nostalgia theme like with the Spellbomb cycle. Another theme is Mirrodin's identity associated with equipment and indestructible.)
- Other color theme 1 ...N
- Planeswalker And/Or Legendary
- Tribes 1, 2, 3 ...N (if applicable) NOTE: Use the art descriptions and/or token card to portray tribes on non-creature cards
- Other supertype/subtypes
- Represent ratios in set in the pack (Eg. Scars of Mirrodin having a large amount of artifacts)
- Marks (Eg. Phyrexian, Mirran) and their respective ratios (20% of cards being Phyrexian mark = 2 to 3 cards in the pack marked as Phyrexian)
- Other unique factors.
All these elements need to be present on the cards in your pack. You'll most likely have cards that need to pull double or triple-duty on fulfilling required elements.
I realize that some of these elements may be argued for whether they need to be included. For example, the nonbasic land can be argued, or the fact that there doesn't need to be a legendary/planeswalker or Melvin or Vorthos card. You can say that the point isn't to cater to each of the individual psychographics or to make sure that all of the different kinds of card colors or card types need to be present in the card.
However, it is my belief that, if you're going to get as close to perfect as you can in a booster pack, not only will your pack represent your set in the best way possible, but it will also include something for everyone or something for anything that anybody would want to seek in a pack. It's not only fulfilling the challenge, it's also going the extra mile to get that much closer to perfect. And that's what I think these perfect packs will need.
So, finalists, similar to how Mark Rosewater goes over how he fills out the design skeleton for the commons of a fictional small set in the Nuts & Bolts article "Design Skeletons in the Closet", you may want to be assigning each of these elements to the different slots to see how your pack will come together before too much designing is done, otherwise, you may find that your last few slots might not match up perfectly in fulfilling every element you're looked to include in the pack.
I hope this helps! I'll revisit this post in the future after the finalists send in their submissions, so I can apply the feedback I receive from readers of this post as well as tackle this challenge for my own set.