Eidolon of Rhetoric

The symmetry is the whole point, and it cuts in a specific direction. A spell-per-turn restriction sounds even-handed, but it does not hit both sides equally: the deck building toward a single high-impact play each turn (a control deck, a tempo deck, a creature midrange deck) barely feels it, while the deck whose plan is to chain multiple cheap spells into a turn (storm, ritual-fueled combos, go-wide token dumps, prowess sequencing) finds its entire engine throttled to one trigger. That asymmetry-disguised-as-symmetry is the design idea, and the 1/4 body is engineered to match it: too small to threaten, too durable to die to the incidental burn and ping effects the very decks it punishes tend to run. It is a lock that asks to be left alone rather than answered, and answering it costs the kind of spell-economy that the locked-out player can least afford to spend. The lineage runs through other once-per-turn taxers like Arcane Laboratory and Rule of Law; folding the effect onto a creature is the wrinkle, trading the bulletproofness of an enchantment for a clock and a blocker, while still living in the enchantment-removal zone for anyone willing to spend a card. White has long owned this kind of resource-rationing prison piece, and this is one of its more pointed expressions: a hatebear whose job is not to attack but to make the other player's best turns illegal.