Fire Emblem Cipher releases a new Booster Series every three months (quarterly). Each Booster Series has at least 100 different cards, with rarities currently spanning from Normal (N), High Normal (HN), Rare (R), and Super Rare (SR). Depending on the Season, they are various kinds of Secret Rares (+X, N+X, R+X, HR) available as well.
Each Booster pack comes with 10 cards. A Booster box contents 16 Booster packs as well as exclusive promo cards, marker cards, and/or sleeves that can only be obtained by opening a Booster box.
The card ratios for Series 1-3 are as follows: Normal (48), High Normal (24), Rare (16), and Super Rare (12). From Series 4 onward, these numbers were balanced to: Normal (42), High Normal (30), Rare (16), and Super Rare (12). Within each Booster box, there is a guaranteed chance of one R+ and the off chance of having an SR+ or Secret Rare instead. there are a number of R+ and SR+ cards. However, they did away with R+ cards from Series 17 onward.
It was not until Series 5 that some of the R+ and SR+ cards began to have different art than their R and SR versions. Some of the plus cards are even signed by that character's illustrator or voice actor which increases their value.
There are various types of Secret Rares currently: HNX, N+X, R+X, and Hero Rare (HR). The +X cards very similar to their normal cards, but some feature variant art, card borders, and some even have slightly altered skills like B09-034N+X Delthea. Series 17 is special as it featured characters from across all Fire Emblem games. From Series 18 onward, each box is guaranteed 4 SRs and the chance of a HR or SR+ instead as noted above. Hero Rares (HR) feature Main Characters who are not already featured in that set. These cards are similar to R+ card styles and feature simpler skills which make them easy to use and play. All Secret Rares are listed at the end of each Booster Series page.