Belial, the Fourth Generation

You may sacrifice two artifact Vehicles you control rather than pay Belial, the Fourth Generation's mana cost.
Flash, flying, vigilance, indestructible, third-gen AS, mount 4 (Only one pilot can crew this vehicle, with power 4 or more. Add the crewing pilot's power onto this creature's power.)
{x}, {t}: If crewed by Leonard Testarossa, deal X damage to any target.