Stand or Fall

The Lady-or-the-Tiger problem rendered as a Magic enchantment: split a defender's creatures into two piles, let them choose which pile may block, and however they decide, half their defense sits out the turn. The cleverness is that the worse their board looks from your seat, the cleaner the cut, because a single dominant blocker can be isolated in the pile they cannot afford to abandon, forcing everything else to stay home. The effect's durability comes from recurrence: every combat on your turn, the defender re-faces the same impossible division, so in a deck built to swing each turn it functions as a soft Falter on a loop. This belongs to the forced-choice school of red combat manipulation, where the opponent's own agency becomes the lever instead of the obstacle, and it is one of the more elegant statements of that idea precisely because the card never dictates an outcome: it only guarantees that whatever the opponent picks, they pick against themselves. The four-mana price buys a permanent engine rather than a single attack step, and the timing is friendlier than it looks: cast in your pre-combat main phase, the combat trigger still fires that same turn. Multiplayer is where it compounds, since the split is applied to each defending player independently, multiplying one dilemma across the entire table.