Gallantry

The whole card hinges on a single word: blocking. By restricting the +4/+4 to a creature that is already in a block, the design steers the effect toward defensive two-for-ones (eat an attacker, keep your creature, draw a card) and slams the door on the offensive blowout where a pump spell turns a marginal attack into lethal. The targeting clause also doubles as the card's own honesty check. A blocking creature only exists once blockers are declared, so an opponent who reads the open mana and declines to attack leaves the spell stranded in hand with no legal target. There is no eject button: the draw is a payoff for landing the ambush, not a consolation for whiffing on the read. That asymmetry is what keeps a two-mana instant that replaces itself from being Giant Growth with a free draw stapled on. The cantrip makes the rate feel fair when the trick connects, netting you a creature and a card, but the conditional target still forces you to bait the swing rather than dictate it. Folding a draw into the boost is what lets a combat trick justify its slot when the math breaks your way. Strip the blocking requirement and you get a stronger card but a worse one; the restriction is precisely what prices the draw.