Rat Out

Splicing a small body onto a shrink effect is old news; the optional target is the design choice worth flagging. Most reactive combat tricks turn into dead cards when the opponent gives you nothing to react to, but pointing the -1/-1 at "up to one" creature means you can simply decline the target and pay one mana for a black token that adds to the board. The shrink handles the low end of the curve (mana dorks, one-toughness utility creatures, X/1 tokens) and, stacked with combat math or another point of damage, reaches a little further up. The token's inability to block is the honest cost: it will not brick your opponent's attack, so this is a proactive engine piece rather than a defensive one. Both halves feed the same graveyard-and-sacrifice ecosystem: the Rat is fodder, and the -1/-1 doubles as a kill button on your own one-toughness creature to trigger a death payoff. Neither mode ever leaves the spell stranded, which is the entire point of the split. It belongs to a long line of black one-drops that ask you to value bodies as much as removal, dividing a single mana between a small answer and a small threat and trusting the deck around it to make both matter.