The Alpha-level Motherfucker, Chaos Ghost Rider, Captain Supreme Ass-Fucker. The Lord Discordant is known as one of the most badass motherfuckers ever put on tabletop. Abaddon has nothing on this badboy when it comes to the cool factor. Yes, the Lord Discordant's model really is awesome and badass.
Lord Discordants are a special type of Chaos Lord who have an arcane mastery over machinery, similar to Warpsmiths, which they use to enhance the powers of Daemon Engines, and they can also cause nearby machines to glitch and seize by bellowing profane litanies.
What makes the Lord Discordant so exceptionally badass (other than the bitching cloak) is that they have their own personal Daemon Engine mount in which they ride around and play horsie whilst their combined mere presence is able to short-circuit machinery, shut down augurs, cause servos and actuators to fail, and corrupt Machine Spirits. Their Helstalker mounts use Magma Cutters to force slice open a vehicle they have pinned while their enormous Hypno-Armour Syringes inject scrapcode and Daemonic dataphages directly into the machine's circuitry. Should the need for close combat arise, the Lord Discordant himself lunges forward with a massive Impaler Chainglaive and Mecha-tendrils.
The Daemon Engine hungers for the Motive Force and once it NOMNOMNOMs this essence, this harvested energy is then used to reinvigorate other Daemon Engines, or is released as beams to infect the systems of other vehicles. Even after the foe has been beaten, a Lord Discordant continues to prowl the battlefield, searching through wreckage for a sliver of Motive Force that may remain. When such remnants are found, their energy is swiftly cannibalized. Captured Machine Spirits are ceaselessly experimented on, twisting them into myriad data configurations for different interesting effects. In terms of function, it is quite similiar to the Dark Eldar Medusae, just replace the psychic life force with that of mechanical life force.
Lord Discordants are found across the entire Chaos pantheon. Those lords devoted to Khorne make motivators seethe with burning rage and transmute lubricating oils to blood. Tzeentchian Lord Discordants cause vehicles to twist themselves through unseen dimensions, crumpling them into impossibly small heaps of slag. Nurgle Lords cause vehicles to vent internal gasses, while their outer plating sloughs off like a diseased scab. And then of course, we have those of Slaaneshi Lord Discordants who are able to rewire machines to feel constant and excruciating pain.