protective sleeves for cards Protect Your Fucking store or display collectible baseball cards Large Size Protective Card Sleeves,

You can obtain the Cosmoem (2-Diamonds rarity) card by opening Celestial Guardians: Lunala and Celestial Guardians: Solgaleo from Celestial Guardians set

As for least favorite

To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions (such as that of Serpent of the Pass's second ability)

The Kewl Tune deck is full of Tuners and Synchro Monsters you can use to summon Zalen, and with Kewl Tune shooting to the top of the format, Zalens price has been shooting up too

This probably is due to the sheet being organized more regularly, eliminating to a large degree duplicate rares and holos from booster boxes

I'm not sure if this crosses your "no combo" rule, but teaming those cards up with Bloodletter of Aclazotz or Wound Reflection leads to one-hit knockouts