I've noticed that each gametype guarantes a exotic weapon drop atleast once at some point. The loot system for exotics are definitely not random, well maybe exotic armor, but you'll have to do good, no amazing to get exotic loot. My first exotic was the Plan C, I believe I went 40 or more kills in Clash, with like 2 or 3 deaths. Then I got the Hard Light from going 23-0 in Rumble. Last night I went 36-0 in Skrimish and got the Universal Remote. You might notice a notification in the kill feed at the end of a game if you didn't die that says "Your prevail was unbroken" I believe that gives you a better chance at a exotic reward. Also, I Never get Legendary engrams any more, It seems like you're most likely to get Legendarys around 21-25 Light randomly, but for some reason whenever I would deal the final blow with a super around 21-25 Light, I got one. I actually got a Legendary, 2 games In a row from the final kill with a super. But I don't know, that's just what I think about the Legendary engrams, but the Exotic weapon drops are not random. The game probably calculates what exotics you have and don't have through your Grimorie Cards when it decides you did good, and you deserve a exotic. But it's just my opinion. [spoiler]13 exotics, 7 more to go intill the Dlc hits.[/spoiler]