Graven is an EL 11 encounter by himself, but he’s rarely out of calling distance of his ally and friend Ridden Favor, a 9th-level half-elf artificer and member of House Lyrandar. The two of them are airship pirates and are likely to be encountered if the PCs are traveling by way of the Zilargo vessels. Graven is notorious in several nations, and many houses have placed a bounty on his head.
Along with Ridden, Graven acted as a privateer in the service of Breland during the Last War. Unsure of what to do with his life afterward, he allowed the artificer to talk him into continuing their former activities. Graven knows that many other spellcarved consider him an enemy. When enmity is declared against him, he uses the day of truce to put as much air between himself and his foes as possible.
As far as pirates go, Graven tends to be an honorable sort, rarely using trickery to take other vessels and treating their crew well so long as they offer no serious resistance. Ridden is his lieutenant, but he tends to cast his spells on Graven before battle and then stay out of sight. Graven sometimes sends Ridden into cities to learn the shipping routes of choice cargo being transported by air or by caravan, and on such missions, Ridden usually adopts some outlandish cover using his hat of disguise.