Each Set Booster box contains 30 Set Booster Packs. While supplies last, purchases of Set Boosters are eligible to receive the Buy-a-Box promo.

From the publisher:

Set Boosters are designed for those times when you just want to have fun opening a pack of cards. They are a joy to look through from start to finish and contain a guaranteed foil and up to four rares and/or mythic rares. Here's what you'll find inside:

• • 1 Snow land (basic or dual land, possibly foil)
  • 1 Rare or mythic rare (can be showcase or borderless)
  • 1 Snow common or uncommon, showcase uncommon, or exclusive rare (see below)
  • 1 Foil card of any rarity (can be showcase or borderless)
  • 1 Non-foil card of any rarity (can be showcase or borderless)
  • 7 Commons and uncommons
  • 1 Art card (1 in 20 are foil-stamped)
  • 1 Ad card or card from The List

For the first time, Kaldheim contains 20 cards (5 rares, 15 uncommons) that can be found exclusively in Set Boosters and Theme Boosters (you can also find the rares in Collector Boosters, and a handful are included in Commander decks). These cards are geared for casual play but are 100% legal in Standard.