Weed-Pruner Poplar

The timing window is the whole catch here. The trigger fires at the beginning of your upkeep and the -1/-1 wears off at end of turn, which means the effect lives and dies entirely inside your own turn: it cannot reach across the table to deflate an opponent's blocker after they declare, and it certainly cannot shrink an attacker during their combat. What it does instead is set up your turn before you draw. Soften a 3/3 blocker to a 2/2 to clear a path, kill anything parked at one toughness, peel a point off a token board: the math resets every cycle, so this is a recurring small-creature answer rather than a grind that whittles a fat creature into the dirt. The body has to survive to your next upkeep before it pays anything, taxing you a full turn before the engine turns on. The forced targeting is the real liability. The trigger demands a creature other than this one whether or not a useful target exists, so when your own dorks are the only legal choices, a free upkeep effect becomes a self-inflicted shrink. Built for a patient black deck that wins by accruing, and worth far more than a vanilla five-drop only if the body stays on the table across many upkeeps or gets recast after it dies.