My best guess was that seven is one of the more common numbers for card games where you draw cards and perhaps it won out because it was what Richard Garfield thought people would assume to draw
So, let me get this straight
[129] [130] Promotional crossovers [edit] Wizards of the Coast has introduced special cards and sets that include cross-promotional elements with other brands typically as promotional cards, not legal for Standard play and may not be playable even in eternal formats
In the original DOR, Ritual Summon could be done from sending materials from anywhere on the field and the Ritual Monster would be summoned on the Card Zone where the Ritual Spell was activated
You can also group your cards by rarity, card type, or price
While it was founded in 1991 to authenticate sports trading cards in response to a growing counterfeit market, the PSA began grading Pokmon card in 1999 not long after the trading card game launched