White Knight

The double-white casting cost is the design statement. Wizards could have priced a 2/2 first striker with protection from black at one-and-a-white and called it a constructed staple; instead they walled it behind WW, which says everything about what the card was built to do. White Knight is a mono-white loyalty test, a card that pays the dedicated player and punishes the splasher, and the rate inside that restriction is enormous. First strike turns the 2/2 body into a creature that trades up against most early drops and survives the exchange; protection from black, once it resolves and the body is on the battlefield, blanks most of the entire color's removal suite (no Dark Ritual into Terror, no Drain Life finisher, no Hypnotic Specter beats), unblockable by black's creatures, and immune to black enchantments aimed at it. The card is the prototype for white's hoser-as-creature design lineage, white winning a black matchup on the battlefield rather than the stack, and the template that later cards (Silver Knight against red, Mirran Crusader against black and green) would extend into other matchups. It is also half of a matched pair with Black Knight, the original color-pie mirror that made protection's combat math legible: two 2/2 first strikers that can never trade with each other, because each one's protection erases the other's attempt to deal damage.