The way I did it was by using a rare void fusion rifle all the way. I played mostly rumble matches, and a few control matches here and there. The trick is to stay calm and keep moving. Don't ever sit in a corner and wait for someone to pass by, it makes you more nervous and causes you to over-think. Get a fusion rifle with high impact and low charge rate if you think you're accurate with it, or get one with moderate impact but fast charge if you're not that experienced with fusion rifles. Keep your k/d above 1.00, and you should complete this bounty in no time. I did it in less than 15 matches. If however, none of that works out for you, try getting an atheon's epilogue or word of crota, it will make things much easier I suppose. That's all the advice I got, good luck!