All of the Extra Life Secret Lairs include at least four cards and generally include some kind of bonus card as well
An auto-include for Pir, Imaginative Rascal and Toothy, Imaginary Friend decks, it also combos well in Bant decks with Emiel the Blessed and Workhorse, where you remove your Workhorse counters to blink Emiel until you have more growth counters than a wall with pencil marks at your grandparents house
You can easily obtain one copy for 750 Gems with 10 free packs of Master Pack from the in-game store, although I would recommend running two or three copies in your deck if possible
This guide covers the current top 10 most valuable cards with live JPN market prices, pull rates compiled from 1,000+ pack openings, a full box EV calculation, and price trend analysis
[135] The game initially offered three starting decks but significantly expanded its card collection shortly after release