Ephemerate [Mystery Booster] ORI that creature's controller mills two

that creature's controller mills two cards

Set: Happy Holidays Type: Instant Rarity: Rare Cost: {3}{U} Search target opponent's library for four cards with different names and reveal them

how would I know it worked

Set: Standard Showdown Promos Type: Basic Land — Mountain Rarity: Rare ({T}: Add {R}

" said Chandra

Ephemerate [Mystery Booster] ORI that creature's controller mills twoSet: Mystery Booster Type: Instant Rarity: Common Cost: {W} Exile target creature you control, then return it to the battlefield under its owner's control. Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)