Sphinx of the Second Sun is a mythic Creature — Sphinx card from Commander Legends (CMR), collector number 643. Current market price: $4.68 (foil $12.25), TCGplayer market prices via Scryfall.
Flying At the beginning of each of your postcombat main phases, there is an additional beginning phase after this phase. (The beginning phase includes the untap, upkeep, and draw steps.)