Legendary weapons are ideal for Hard Mode missions in Hounds. You can find these weapons by buying Blue Flame Random Boxes.
Blue Flame Random Boxes are randomly generates Blue Flame weapons. Use to receive an item besides of weapons and material items. Blue Flame Random Boxes can buy on Cash Shop as package of 1 or 6 random boxes.
Here is the list of Blue Flame Random Boxes:
Blue Flame Assault Rifle
Blue Flam Submachine Gun
Blue Flame Grenade Launcher
Blue Flame Minigun
Blue Flame Shield Pistol
Blue Flame Sniper Rifle
Blue Flame Shotgun