The Venom Symbiote bonds with Deadpool, giving him new powers and a stylish monochromatic look, in Deadpool: Back in Black #1 by Cullen Bunn and Salva Espin, the team behind Deadpool and the Mercs for Money. The comic follows directly on Deadpool's Secret Secret Wars, also written by Bunn, which shows the Merc with a Mouth briefly wearing the Symbiote on the original Battleword, before Spider-Man ever did.

Back in Black is also a flashback, set after Spider-Man first rejected the symbiotic alien costume. Since the preview is unlettered, we don't know much else, except that Machine Man is involved somehow, and also some pretty dangerous looking aliens, who I assume have come to Earth looking for the symbiote. Or maybe they're looking for Deadpool. Either way, they're bound to run into him, and into trouble.

 

Variant Cover by Rob Liefeld
Contest of Champions Game Variant

 

Here's the official word from Marvel:

What happens when Deadpool bonds with Venom? Pure mayhem! Today, Marvel is pleased to present your first look inside DEADPOOL: BACK IN BLACK #1 – a brand-new series debuting this October! Fan-favorite creators Cullen Bunn and Salva Espin are back with a brand-new Deadpool tale that ratchets up the chaos to completely new heights! Remember when Spider-Man rejected the alien symbiote way back in the day? Did you know that for a period of time, the symbiote went slinking back to Deadpool on the rebound? No? Well you do now! And you won’t believe the damage Deadpool can cause when he’s packing a nigh invulnerable alien symbiote. The fireworks begin this October when DEADPOOL: BACK IN BLACK #1 comes crashing in to comic shops and digital devices everywhere!