Here are the card counts and likelihood of getting each type of card: 4 Rares and 3 mythic rares with the serialized double rainbow Ravnica City treatment There are 250 copies of each serialized rare and mythic rare card for a total of 1,750 total serialized cards in Collector Boosters
A giant portion of the set was 2-3 color cards and players would often play 3-5 colors in their limited decks
These unscrupulous individuals buy up stock in bulk to resell at an absurd mark-up, which is why you'll often see Final Fantasy cards going for a ridiculous price
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Decks somewhere in between, of course, will see the most benefit, but as it stands, Renari is a flexible and powerful role player Id be happy to shortlist for my deck
Even if you open Ancient Tomb #46 (the second cheapest), you still opened one of the most valuable cards in the bonus sheet (and set in general)