Library: Your library is your full deck of cards, with all the lands and spells you can play
If you dont mind using external tools, then Reddit user maxwell1755 created a useful spreadsheet that allows you to keep track of what cards you own and which cards you need, including a handy Mew Tracker table that calculates the total number of missing cards in each pack, and also shows which pack has the highest likelihood of containing a new card
Unfortunately Arikawa still eventually lost due to time, but he could almost mount a comeback with Altergeist Meluseek while Ito has two set monsters
5 Omnath, Locus Of Creation - 17 Days Omnath, Locus of Creation was banned from the strategic trading card game in October 2020 after just 17 days in Brawl and Standard formats (via Magic Wizards )
Reaper of the Wilds is a highly powerful midrange card that needs no building around to tap into the power like Glissa requires of you
Gardevoir is a stage 2, fairy type Pokemon card, with an hp of 130