Collector Boosters are the best place to get rare and mythic rare Booster Fun cards. Commander Legends: Battle for Baldur's Gate Collector Boosters contain a total of six rares and mythic rares:

1 Foil-etched rare or mythic rare legendary creature or Background
1 Traditional foil Booster Fun or extended-art rare or mythic rare
1 Non-foil rulebook or borderless rare or mythic rare
1 Non-foil extended-art rare or mythic rare from the Commander Legends: Battle for Baldur's Gate set
1 Non-foil extended-art rare or mythic rare from Commander Legends: Battle for Baldur's Gate Commander set
1 Traditional foil rare or mythic rare
1 Foil-etched common or uncommon legendary creature or Background
1 Traditional foil common or uncommon legendary creature or Background
1 Traditional foil rulebook common or uncommon
1 Traditional foil basic land
2 Traditional foil uncommons
3 Traditional foil commons
1 Traditional foil double-sided token

Contents:
1 Sealed Collector Booster Pack
‣ 15 Randomized Cards

MtG: Battle for Baldur's Gate collector's booster