Adventures in the Forgotten Realms Set Boosters contain:
At least 1 rare or mythic rare card (approximately 27% of Set Boosters contain 2 rares or mythic rares, 3% contain 3, and it's even possible to open 4 though that's less than 1% of the time.)
1 Traditional foil card of any rarity
1 Rulebook, module, or borderless common or uncommon
1 Art card or foil-stamped art card
7–10 Commons and uncommons (at most 7 may be uncommon)
1 Basic land or foil basic land
1 Ad/token/dungeon card or 1 card from The List