From GameWatcher: "Drakgoon is a big, bad gun if we've ever seen one. This Grineer flak cannon fires a large number of slash pellets whose spread and punch-through depends on how long they've been charged. Add their bounciness to the mix, and you've got a bucket of fun.
Of course, the Drakgoon does look slightly like a bucket all on its own, but it's rather badass still. When combined with its Fomorian Accelerant Augment, Drakgoon gets amped up to eleven. Read more on that, as well as how to actually get the Drakgoon, just below."