A full team of Black Hammers w/ Weapons of Light and Time's Vengeance is the single most powerful option against Atheon. Rockets and Grenades have the effect of causing Atheon to try to find a way to gain distance from Wolfpack Rounds and Grenade clusters. This disables efficiency in sniping Atheon's misplaced weak spot. So basically, while one player is getting off a decent amount of damage once on Atheon, it causes teammates with the more efficient weapons to slow down their firing by a lot. Feel free to go playtest the damage, if you feel the need. I, for one, see exactly where the OP is coming from.