You know everyone can see your stats right? You've only started 219 story missions and actually finished 89 of them. On top of that your a level 30 so you've played plenty before doing Fist of Crota. 500+ attemps are most likely closer to 50 attempts, keep trying. Note: I was trying to get it on fist of crota but gave up. Went to the moon on patrol and killed the blade of crota with a rare pulse rifle to get it. I thought maybe if I wasn't killing him with an already upgraded exotic or legendary weapon it would be more likely to give me the husk. Got it first try.