I can't see Gantz lending them a hand at all. Whatever happens. If Nuri kills the Gantzers, the mission is just over and Gantz will bring in new people to use and terrorize.
Not that it'll happen. Somehow they will get rid of Nuri for us and I don't think that too many of them will die in the process.
But it'll probably take at least 5 chapters until it's done.
"For Feanor was made the mightiest in all parts of body and mind, in valour, in endurance, in beauty, in understanding, in skill, in strength and subtlety alike, of all the Children of Illuvatar, and a bright flame was in him"