Basically, the title, the "feed the void" aspect on warlocks, feels pretty lackluster, especially when comparing it to a fragment that has so much more usability. When using "feed the void", devour should grant the benefits of the "dark matter" perk from the void warlock middle tree, where getting a void ability kill would now grant melee and class energy in addition to health and grenades. That would definitely make it stand out from the fragment.