Glen Elendra Archmage

Persist is the engine that turns one counterspell into two, but the body is what makes the trade unfair. The activated ability sacrifices the Faerie to counter a noncreature spell at the cost of a single blue mana; that death satisfies Persist's no-counter condition exactly, so it returns shrunken to a 1/1 and stands ready to do it again for another blue. That shrinking counter is the natural ceiling: the rebought version dies for keeps the second time it is sacrificed, so this is a clean recurring two-for-one rather than a lock. The cost still matters: each counter asks for blue mana untapped, so the permission is not free, just so cheap and so repeatable that an opponent leaning on instants and sorceries has to respect it across two turns. The target restriction is the load-bearing constraint. It touches nothing on the creature side, which keeps it from being universal permission, but it makes combo and control plans that hinge on a key spell deeply uncomfortable to assemble, since the same card answers the linchpin twice. Killing it once only resets the clock; bounce, exile, or a -1/-1 effect that denies the rebuy is required to be rid of it. Flying keeps it from idling when there is nothing to counter, chipping in and trading in the air. Permission stapled to an evasive blocker that has to be killed twice sits at an intersection of tempo and disruption few four-mana creatures reach.