Shrivel

In Commander, Shrivel fills a specific niche: cheap, instant-speed board sculpting against token decks and aggressive x/1 packages like Elves or Goblins. It doesn't threaten a Craterhoof Behemoth, but it can wipe a field of Thopters at the end of an opponent's turn for two mana, which is a legitimate play. In Pauper, where x/1 creatures are common and resources are tight, Shrivel earns real consideration as a sweeper that leaves larger creatures standing. Legacy and Vintage have strictly better options at the same slot, so it doesn't see play there despite being legal. Pioneer and Modern have access to stronger mass -1/-1 effects, which keeps Shrivel off those radars except in the most budget-conscious builds.