Across the Multiverse [Unknown Event] Elf Shaman Some Set Boosters include a

Some Set Boosters include a card from Magic's past

the content from the associated movie or short is introduced to the game

Set: Introductory Two-Player Set Type: Artifact Rarity: Uncommon Cost: {4} {3}

or one of the Kaldheim Commander Deck rares or mythic rares—see the section on Sagas above for more about this slot

Across the Multiverse [Unknown Event] Elf Shaman Some Set Boosters include aSet: Unknown Event Type: Enchantment Rarity: Common Nontoken creatures you control which aren't from the MOM main set get +1 +0 and gain haste. (This includes Multiverse Legends, playtest cards, cards from Mystery Booster, and anything else not from the MOM main set.)