Any DOT grenade would've killed them if they are to stupid to move off the zone. I rarely get killed by lightning grenades as soon as the first pulse hit just jump away. Also I got a breaker medal with a scatter grenade. I've gotten multi kills with many grenades. And one time an arc warlock wiped out 4 or 5 of us on a zone with arc web. There was no escaping those either at least the lightning nades give you a window to stay alive.