Defiant Vanguard is a special Creature — Human Rebel card from Time Spiral Timeshifted (TSB), collector number 5. Current market price: $0.29 (foil $0.70), TCGplayer market prices via Scryfall.
When this creature blocks, at end of combat, destroy it and all creatures it blocked this turn. {5}, {T}: Search your library for a Rebel permanent card with mana value 4 or less, put it onto the battlefield, then shuffle.