Meeting of the Five is a mythic Sorcery card from Streets of New Capenna Promos (PSNC), collector number 202p. Current market price: $0.37 (foil $0.61), TCGplayer market prices via Scryfall.
Exile the top ten cards of your library. You may cast spells with exactly three colors from among them this turn. Add {W}{W}{U}{U}{B}{B}{R}{R}{G}{G}. Spend this mana only to cast spells with exactly three colors.