Tectonic Edge
Land
: Add 
.
, , Sacrifice this land: Destroy target nonbasic land. Activate only if an opponent controls four or more lands.
"We move because the earth does." —Bruse Tarl, Goma Fada nomad
Vincent Proce
Commander 2014 (C14)
• #313Rulings
Tectonic Edge’s second ability checks how many lands an opponent controls only at the time you activate the ability.
(wotc • 2010-03-01)
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).
(wotc • 2010-03-01)
Rulings
Tectonic Edge’s second ability checks how many lands an opponent controls only at the time you activate the ability.
(wotc • 2010-03-01)
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).
(wotc • 2010-03-01)