Final Round Timur's Lash would make an interesting finisher for a Fusion Rifle. If you only take off a little over half their HP, a Final Round to the body would finish them off. I would keep the one with Rangefinder/Field Scout/Crowd Control, personally. If you play a lot of team based modes there are plenty of scenarios where you'll finish off one player, then be grateful for the bonus damage and extra ammo letting you for sure 2HKO the others. Devil You Know + Crowd Control can also 2HKO and fires faster but if an enemy has even a single point of Armor, it becomes a 3HKO. Plus it's always at least a 3HKO when you don't have a damage bonus, unlike Lash which can 2HKO tons of those Recovery/Agility Warlocks and Hunters.