Then you are drawing a card
First introduced in Shadows over Innistrad back in 2016, this mechanic solved a problem we didnt even know we had, how to keep the cards flowing without breaking the game
Fabled Princesses Lorebook 9-Pocket Card Portfolio
Then for the next two turns, like most lifelink fliers would, Phoenix dominates the board and makes it almost impossible for you to lose a damage race, before it floods the board with creatures and gets ready to transform again
Using the Undying mechanic, Yawgmoth can quickly get into infinite combo situations where he continuously draws cards by sacrificing Undying creatures
Even beyond the dual lands, Wizards could spend the next several years making piles of money selling foil Mox Diamonds, Moats, Gaea's Cradles, and Mishra's Workshops, and these are only the most expensive of the Reserved List cards