Riddleform

The trick is that it fights like a flier but only exists when you decide it should. The animation triggers off casting a noncreature spell, not resolving one, so the 3/3 Sphinx forms while your instant or sorcery is still on the stack. And the trigger uses "may": it offers the transformation, it never forces it. Left dormant, the card is a plain enchantment, immune to creature removal and offering nothing an opponent can profitably kill. During your opponent's main phase, when their sorcery-speed removal is live, you simply leave it inert: there is no legal creature to point at, because you never woke it. That optionality is the entire design. Once you do commit, the body reverts in cleanup, so an instant-speed answer held for the right beat still connects; the protection is a choice you keep making, not a wall that stands on its own. The scry ability is the floor beneath the beatdown plan, a mana sink to dig with when the clock stalls, so the card is never fully dead in a lull. The flier is a reward for a deck already slinging noncreature spells, and the player who decides when it exists is the same one deciding when it is safe to swing.