Desperate Measures

Black has always paid for card draw with life or tempo; this pays with a creature's shrinking toughness, and the elegance is that the two halves of the effect feed each other. The +1/-1 is setup and payoff at once: it can kill an X/1 outright, but more often it nudges an already-damaged blocker or a token below its toughness, and if that creature dies under your control before end of turn, the reward is two fresh cards. The dying clause is what makes it more than a shrink spell, and the "under your control" wording is the constraint doing the real work: the draw only triggers off your own creatures. That points the card squarely at go-wide token decks and sacrifice shells, where you already want fragile bodies to die on your terms. Read on your own one-toughness creature, it turns a body you were happy to trade away into two cards for a single mana; read on a token you were about to sacrifice anyway, it stacks the death trigger with whatever payoff you already had lined up. Point it at an opponent's creature and you get a modest combat trick with no draw attached, the honest floor the design accepts to keep the ceiling clean. The instant speed matters: you can hold it as a combat surprise or wait for a creature to soak up damage, then finish it and refill in the same window.