Hollow Dogs

Five mana for a body that swings as a 5/3 is a rate that never asked anyone to do anything except attack, and that is exactly the point. The attack-trigger pump is the whole design: toughness stays at 3 so the card cannot moonlight as a blocker, while the power jumps every time it commits to combat. The buff lasts only until end of turn, so this is a perennial attacker rather than a wall: it wants to be the one swinging, and it shrinks back to a 3/3 once the turn ends. There is still a trigger lurking, so it is never inert; it simply offers nothing on defense, because the reward is gated entirely behind the declaration of attackers. What dates the card is the cost: paying five for a creature whose offensive ceiling tops out at 5/3 reads as steep now, and the era's filler black beaters have largely been outrun by leaner aggressive bodies. The template, though, is clean and durable. The "gets bigger when it attacks" hook is one designers have returned to repeatedly, refining the rate and trimming the cost while keeping the same behavioral nudge intact: this creature belongs in the red zone, and the rules pay you only for putting it there.