Flying
Historic spells you cast cost {1} less to cast. (Artifacts, legendaries, and Sagas are historic.)
A spell is historic if it has the legendary supertype, the artifact card type, or the Saga enchantment subtype. Having two of those qualities doesn't make a spell more historic than another or provide an additional bonus—a spell either is historic or it isn't.
The last ability of Jhoira's Familiar doesn't reduce its own cost while you're casting it.