The tether from Vateshran staff does not always break when an object comes between players. Additionally, it often takes more than 2 seconds to break after being behind an object, assuming that object is actually capable of breaking the tether. If a player hasn't spent enough time behind the object, the tether will remain attached. Not every tree, or pillar, or wall will actually cause a break. These objects will generally prevent initial targeting, but not if the tether is already attached.