Xianyun, Steward of the Skies

Landfall - Whenever a land enters the battlefield
under your control, choose one:
• Untap another land you control, it becomes a 3/3 elemental creature and until end of turn, it gains
flying.
• Put a prosperity counter on another target land
you control. lands you control have "{t}, add X
mana of any one colour among colours of mana
this land would produce, where X is the number of
prosperity counters on this land."