Whats up man I had the same problem. Some of it comes down to practice and other times lag. Tricks I have learned as a hunter you have time to get right next to him. Your in charge tell your team to down crota when you are underneath him not before when your still on the rock. Stand behind crota if possible I have seen this help as well. Another tip is you be the host/fireteam leader go into crotas end alone and have everyone join you. Crouch on rock turn invisible and jump up on platform down crota rt rt rt press y drop sword and blink back away from crota and then puck up sword. When running away run towards the opposite side crota is running too. Your in charge thou! You tell your fireteam what to do and when to do it. No room for backseat drivers in crotas end.