The Immortal Sun is a mythic Legendary Artifact card from Rivals of Ixalan Promos (PRIX), collector number 180p. Current market price: $14.69 (foil $20.66), TCGplayer market prices via Scryfall.
Players can't activate planeswalkers' loyalty abilities. At the beginning of your draw step, draw an additional card. Spells you cast cost {1} less to cast. Creatures you control get +1/+1.