The bloated corpse of a decaying gigantic creature is necromatically enhanced and fused with an undercarriage for use as a grisly and terrifying airship. The methane gas from tissue decay keeps it buoyant in atmosphere, but it can be even more flammable than hydrogen if it escapes...
There are two major (read feuding) provinces in the kingdom. The Lord of one is secretly a mad, power-hungry despot, constantly plotting against the king. The Lady of the other is secretly an ancient silver dragon.