Hell Blade
The Hell Blade is the Chaos Space Marines' interceptor. It is produced by the heretic Forge World of Xana II, who sell their wares to anyone who will supply the souls and flesh to make more daemon engines, and Chaos Space Marines deliver.
Not that Chaos Space Marines fly them themselves, though -- they don't think that flying a machine brings as much glory as fighting in person, so they wire in a servitor to fly the Hell Blade instead. Said servitor is permanently bonded with the partially-daemonic flyer, so it can only gain sensations to disrupt its boredom by swooping around and shooting things. It's not as tough as the Heldrake, and it doesn't have the flamer or claws, but it is wickedly fast and sports a mean set of autocannons (four twin-linked shots). On and off the table, they are cheap and easily fielded in vast quantities, so Chaos Space Marines will fill the sky with them to establish air superiority before sending in the heavier flyers.
History
The Hell Blade was first given rules in Imperial Armour Update 2006. It was a Fast Attack choice for Chaos Space Marines, and Heavy Support for the Lost and the Damned. Forge World also included it in the Chaos army list in Aeronautica Imperialis.
It was updated in Imperial Armour Volume Six as a heavy-support choice for the "Servants of Decay" and "Servants of Slaughter" variants of the Renegades and Heretics army list as well (they only showed up when the leadership of Vraks went full Chaos). It got moved to Heavy Support for the Chaos Space Marines as well. Imperial Armour Aeronautica made it fast and agile with the new flyer rules of 6th edition, knocked a few points off its price, and moved it back into fast attack (for CSMs). Imperial Armour Volume Thirteen gave it an optional Autocannon upgrade (which you should always take - six twin-linked Rending shots) and a "you should have shot at where I was going to be" superpower that gives it an invulnerable save and a little extra reach. It was FAQ'd to make it an Interceptor in games using the Death From the Skies rules.
In 8th Edition it gets two Helstorm cannons that have lower strength but higher AP than a normal autocannon and the option to swap them out for lascannons. It maintains an invulnerable save and good maneuverability while keeping a respectable cost, but lacks some of the dakka it once had.