Mysterious Confluence is a rare Instant card from Unknown Event (UNK), collector number RC05a. Current market price: $19.00, TCGplayer market prices via Scryfall.
Choose a card at random from among Righteous Confluence, Mystic Confluence, Wretched Confluence, Fiery Confluence, Verdant Confluence, Brokers Confluence, Cabaretti Confluence, Maestros Confluence, Obscura Confluence, and Riveteers Confluence. Create a copy of that card. You may cast the copy without paying its mana cost. (Roll a D10 to determine the random card.)