I'm stuck on the final task of the exotic weapon bounty , a light in the dark, and upon completing it, I'll be rewarded with what maybe the most powerful, if not, broken exotic hand cannon on Destiny known as thorn.

Allow me to explained the final task (spoiler alert if you want to get the hand cannon on your own); the objective of the final is to take out a special hive wizard call , Xyor the unwed. He appears during the battle with the abomination, Phogoth, boss fight in the 3rd wave enemies when the phogoth has almost quarter health left. Kill him first before continuing after phogoth to finish it off.

I'm stuck on the door that leads to the next room which is locked and you need your ghost to decrypt the lock. But you need survive 3 waves of brutal , heavily shielded and aggressive enemies which includes majors and ultras.

I'm seeking a new fire team who are willing to help me and do not expect to turned down of being rewarded. I am willing to join your clan or anything for that matter in return.

Please help on the final task of the exotic bounty, a light in the dark bounty.