Do something with them. First off the Immobius perk should be usable for all subclasses, because it goes that way for warlocks' and hunters' exclusive guns. I think the Immobius perk should be "Ammo is not expended when standing in ability field." So that means shooting while inside your bubble with any perk, your aftermath, or sunspot won't expend ammo. Then Fabian Strategy should get stat buffs and the front line perk should be "Increased armor when enemies are near" (one enemy).