Brilliant Ultimatum is a rare Sorcery card from Shards of Alara (ALA), collector number 159. Current market price: $1.31 (foil $8.56), TCGplayer market prices via Scryfall.
Exile the top five cards of your library. An opponent separates those cards into two piles. You may play lands and cast spells from one of those piles. If you cast a spell this way, you cast it without paying its mana cost.