Halo Fountain is a mythic Artifact card from Streets of New Capenna Promos (PSNC), collector number 15p. Current market price: $8.91 (foil $10.06), TCGplayer market prices via Scryfall.
{W}, {T}, Untap a tapped creature you control: Create a 1/1 green and white Citizen creature token. {W}{W}, {T}, Untap two tapped creatures you control: Draw a card. {W}{W}{W}{W}{W}, {T}, Untap fifteen tapped creatures you control: You win the game.