It DID ensure a fourth kill, so long as you could find a fourth person back before it was nerfed. Immolation Fists offers a situational perk from the skill tree; Explosive Pyre alone isn't strong enough to justify nerfing Hammer of Sol. Celestial Nighthawk has its obvious tradeoff, being one shot like you stated. Impossible Machines offers a situational perk from the skill tree..But is pretty much the only Stormcaller Exotic around right now which is probably why it's overused. I can see an argument as to why it's too strong, though. Mask of the Third Man hardly benefits Arcblade after testing; it doesn't need a tradeoff really The Ram, No Backup Plans, and Peregrine Greaves don't even relate to a Super ability whatsoever. The Ram gives Voidwalker Melees Life Steal and +3 armor (Was nerfed with TTK due to being the only viable Warlock option), No Backup Plans activate Force Barrier on a Shotgun kill which CAN synergize with Ward of Dawn but isn't solely there to benefit it, and Peregrine Greaves buff Shoulder Charge when used in the air..Which isn't even a Super ability. -Edited for clarity-