Jhoira's Familiar

Historic exists almost entirely to give a handful of enablers a clean noun to point at, and a flier that discounts everything under that umbrella is exactly the payoff the keyword was invented to enable. The reduction reaches a wider net than a typical artifact discount: it shaves a generic mana off every legendary creature, every Saga, and every artifact you cast, which in a deck stuffed with those types compounds faster than a flat ramp piece ever would. That breadth is also why the body stays a plain 2/2 for four; the stats do nothing on their own, so the reduction has to carry the card, and it only carries it in a shell deliberately overweighted toward historic permanents. The real friction is the obvious one: a cost reducer that lives on a creature dies to any removal aimed at it, and it only affects spells you cast while it is on the battlefield, so a chunk of its value evaporates the moment it leaves. It rewards getting the Bird down early and keeping it alive across several casts rather than dropping it as a topdeck and hoping for one big turn. Glue for a deck that has already committed to the type line it cares about, and dead weight in one that hasn't.