Nahiri's Lithoforming

• WWizards of the Coast2020-09-25
  Official Ruling
  You don't sacrifice lands until Nahiri's Lithoforming is resolving. Once you do so, players can't take actions until the spell has finished resolving.
• WWizards of the Coast2020-09-25
  Official Ruling
  Nahiri's Lithoforming's permission to play lands is cumulative with other effects that allow you to play additional lands, such as that of Scale the Heights.
• WWizards of the Coast2020-09-25
  Official Ruling
  If an effect says that a land enters tapped unless a condition is met or a cost is paid, that land enters tapped even if that condition is met or that cost is paid if it's affected by Nahiri's Lithoforming.
• WWizards of the Coast2020-09-25
  Official Ruling
  If X is greater than the number of lands you control, you sacrifice each land you control. The number of cards you draw is less than X, but you're allowed to play X additional lands.

Rulings via Scryfall