Wall of Wood

Pay one green mana, get three toughness, get nothing else: that is the rate this 0/3 sets, struck in the era before each color's wall had a settled price. The toughness is the entire point. Three blanks the period's one-drops and holds the line against most early attackers, and a single green mana is the cheapest possible price for that wall. With zero power, it never threatens anything back; it exists purely to absorb, the most honest expression of defender green ever printed. Everything green has done in this space since reacted against the baseline this card established. Wall of Blossoms attached a cantrip, Wall of Roots attached mana production, Sylvan Caryatid attached fixing and hexproof. Each is a study in how Wizards learned to bolt upside onto defender without breaking the underlying rate. Wall of Wood itself stayed pure, and that purity is what dates it: the card that defined what a French vanilla green wall was worth, before green walls started doing more than walling.