Borne Upon a Wind

What Vedalken Orrery does for a whole game, this does for a single turn, and it replaces itself while doing it. The blanket flash grant is the interesting half: it applies to every spell you cast that turn, not one, so the two mana buys you a window rather than a single trick. That reframes the deckbuilding question from "what do I flash?" to "what does my opponent leave open?" You untap with lands available, pass the turn holding a two-mana instant, and then unload your sorcery-speed plan (a planeswalker, a board wipe, a big threat, a full turn of development) at the end of their turn or in response to their attack. Because it grants flash as a blanket effect rather than a one-target buff, the ambush can be a sequence: hold up removal, then land a threat, then draw off the whole enabled turn. The cantrip is the insurance policy: when the ambush never materializes, you cast it on your own turn for a card and keep hand size neutral at almost no cost. The permission lasts the full turn, not the length of the spell on the stack, so once it resolves the window stays open through your opponent's entire turn and closes only at cleanup; the payoff is compressing one turn's worth of tempo into their turn, not turning your deck permanently instant-speed. The reward goes to the player already thinking a turn ahead, willing to trade the initiative for the surprise.