United nomad tribes before the attack on the capital in the climax of the story. Although technologically outmatched by the Empress, nomads are able to equal the terms of engagement. Large Monsoons, serpent-like creatures from the far reaches of the Outer Lands, are armored and used both, as a troops transportation and a weapon. Though they are pretty slow and are not particularly dangerous by themselves (apart from their sheer size), augmented with the hoover-engines, they can be used very efficiently as a 'living hovercrafts' and rams. Floating above the ground allows nomads to steer them over sharp rocky terrains that normally keep Monsoons at bay.
Smaller units, called Zephyrs, are used typically for combat. These are fully mechanical, usually composed from elements coming from Desert Trains and shot down Frigates.
A concept for my personal project called 'Absolutum'. The story takes place in a futuristic fantasy-like kingdom in totalitarian setting. The world, full of bio-engineering, meta-alchemy and psionics is ruled by the Empress, a quasi-immortal with powerful psychic powers thanks to her longevity and numerous mutations. The magical substance called Arcalum is the base of her power. Arcalum is used to run machinery and weaponry developed by royal meta-alchemists as well as a high-energy fuel source used in air-frigates. The rule of the Empress is eternal and unthreatened. Or so it seems.