Frilled Mystic

Mystic Snake with the numbers reshuffled, and the reshuffle matters more than the stat line suggests. The older design put hard permission on a 2/2; here the body swings up to 3/2, but the counter works the same way: it targets any spell, and only when the creature enters. Everything meaningful about this card happens on the opponent's turn. Flash plus the enters-the-battlefield trigger collapses a permission spell and a creature into a single four-mana investment held at instant speed: leave the mana open, represent countermagic, and let the opponent decide whether to walk into it. The catch is that the counter is not free insurance. Flash it in at end of turn with an empty stack and the trigger has no legal target, so it simply does nothing; you keep the 3/2, but the Cancel evaporates. The counter is a use-it-or-lose-it window that opens exactly once, on arrival. That is what makes the opponent's outs positional rather than reactive: bait it with a lesser spell, dodge with a mana ability or fetch, or hold the real threat until the mana is committed elsewhere. Killing the Mystic in response does not save the countered spell, since the enters-the-battlefield ability resolves independently of its source once it is on the stack. Removal only trades a card for a 3/2 that has already done its job. That is the bargain: hard permission on a creature that stays behind, bought with a counter that must be spent the instant it lands.