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{1}, {T}: Scry 1. Put a landmark counter on Treasure Map. Then if there are three or more landmark counters on it, remove those counters, transform Treasure Map, and create three Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")
For more information on double-faced cards, see the Ixalan mechanics article (http://magic.wizards.com/en/articles/archive/feature/ixalan-mechanics).
If Treasure Map leaves the battlefield before its ability resolves, you can't put a landmark counter on it. However, if it somehow already had three landmark counters on it before it left the battlefield, you'll get three Treasures.
If a third landmark counter is put on Treasure Map by something other than the resolution of its first ability (as modified by any applicable replacement effects), you won't remove those counters, transform Treasure Map, or get Treasures yet. You'll have to wait until you activate its first ability again.
