Stabbing Pain

The tap rider is what separates this from a generic one-mana shrink effect. On its own, the -1/-1 is modest work: it picks off X/1s, softens a blocker, and trades unfavorably with anything bigger. Add the tap and the spell starts doing tempo work instead. Fired during your opponent's upkeep or in combat, it pulls an untapped attacker off the next swing or removes a planned blocker outright, while the toughness reduction still stacks on top to finish anything already wounded. That double function is the real lever: every cast asks whether you want cheap removal or a one-turn lockdown, and the better read shifts with the board. This is the cheap, card-disadvantage-by-default disruption black has always priced aggressively, the kind of instant that rarely nets a card but buys a turn. The constraint built into the rate is that the minus is only -1/-1 and the tap evaporates at the next untap step, so nothing here is permanent; you are renting a combat phase, not answering a threat. Spend it on the wrong turn and you have burned a card to delay a single attack.