An X spell is also inherently flexible because you pay what you want for X
7 Bob Dark Confidant You might wonder how anyone got "Bob" out of the name Dark Confidant, and that's because it has nothing to do with the name
Icetill Explorer Icetill Explorer is a self-mill card made for landfall decks
The budget-friendly versions of this exact effect are dirt cheap and stack: Marauding Blight-Priest ($0.25), Epicure of Blood ($0.34), and Defiant Bloodlord ($0.39)
Besides, just as WotC wanted Modern to avoid being merely the The No Reserved List Format, they will surely want to avoid the eventual Post-Modern format to being branded as The No Fetchlands Format. Magic Origins is such a clean line to draw
So it wouldn't be that big of a surprise for there to be a functional deck in Standard that could play Zirda as its companion, although I'm not sure just how good Zirda would be in such a deck