If the top card of your library changes while you're casting a spell, playing a land, or activating an ability, you can't look at the new top card until you finish doing so. This means that if you play a land from the top of your library and it has a replacement effect that requires you to make a decision (such as that of Temple Garden), you must make that decision without knowing the next card of your library.

Verge Rangers lets you look at the top card of your library whenever you want (with one restriction; see below), even if you don't have priority. This action doesn't use the stack. Knowing what that card is becomes part of the information you have access to, just like you can look at the cards in your hand.

Verge Rangers doesn't allow you to play additional lands.