Tectonic Edge

• WWizards of the Coast2010-03-01
  Official Ruling
  Tectonic Edge’s second ability checks how many lands an opponent controls only at the time you activate the ability.
• WWizards of the Coast2010-03-01
  Official Ruling
  Assuming you can activate Tectonic Edge’s second ability, you can target any nonbasic land with it (not just one controlled by an opponent that controls four or more lands).

Rulings via Scryfall