Windreader Sphinx

The 3/7 body is the tell that this was built as a defensive draw engine, not an aerial beater. Seven toughness behind flying means it survives the ground stall it encourages and blocks almost anything in the air without dying, so it sits on the board long enough for the trigger to compound. And the trigger is the interesting part: it fires on any creature with flying attacking, not just this one and not just yours. The symmetry even rewards racing into an opponent's evasive board, but the more important consequence is timing. Land it precombat with an established wing of fliers and you start drawing the same turn, because every one of those creatures swinging is a card; the seven mana does not buy a dead turn so much as a payoff that scales with the board you already had. That is the design lesson: a high-toughness flier converts a slow, grindy air war into card advantage by sheer attrition, where most blue draw payoffs at this cost demand you do the attacking yourself, with a single creature, once. The brake is the obvious one. A lone Sphinx with no other fliers draws nothing until it can attack alone, and seven mana is a real investment for a body that wins no race by itself. The condition keeps it honest: it does not close the game, it makes a flying-heavy board run away with the card count, and it asks you to have built that board before it arrives.