Great Defender

Defensive logic scaled to the threat. The design trick is reading mana value off the target itself: pay one white mana and the toughness boost equals your creature's mana value, so the buffer scales precisely with the size of what you are keeping alive. Save a one-drop and the protection is negligible; save the six-mana bomb you spent your whole turn deploying and the boost is enormous, enough to pull it out of burn range or stonewall a trampler mid-combat. That self-scaling clause was unusual for the era, when combat tricks were almost universally fixed-size pumps: Giant Growth and its flat +3/+3, the static buffs of the Strength auras, the rigid numbers of Healing Salve. The mana-value referent creates a quiet floor too: it does almost nothing for a token, which has no mana cost and therefore a mana value of zero, while paying out hardest on the expensive threats you most want to defend (and note it reads printed mana cost, so a creature cheated into play still carries its full value). The pure-toughness boost commits the card to defense, locking it out of the racing and finishing roles Giant Growth occupies, but that restriction is what lets the rate sit at a single white mana. A clean early example of variable-cost-to-effect scaling, where the size of the answer is dictated entirely by the thing it is answering for.