Nyx Lotus is a rare Legendary Artifact card from Theros Beyond Death (THB), collector number 235. Current market price: $4.31 (foil $5.28), TCGplayer market prices via Scryfall.
Nyx Lotus enters tapped. {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)