Expressive Firedancer

In Commander, Expressive Firedancer is a legitimate win condition in spell-heavy red or Izzet decks — with three opponents and a critical mass of instants and sorceries, it converts cantrips and removal into a lethal damage clock. In Modern and Pioneer, it slots into Burn and prowess shells as redundant reach, though it competes with more efficient two-drops and requires a spell to fire before it does anything. Legacy has faster threats and more consistent engines, so Expressive Firedancer rarely makes the cut there. Pauper has no access to it at common, and Standard playability depends entirely on whether a given format environment supports a two-mana do-nothing-on-entry enchantment. Commander is clearly its best home.