As best I understand, it requires double/triple the mob's health within a limited span of time. This is based on some dchat members talking with a dev who was trying to figure out how an OB blast wave had funneled and somehow amplified through LV's center fog gap. It wiped out everything north of hydro, and gibbed several marines. The dev said it had to do over 600 damage to gib a marine.
Agreed. Devs aren't focused on adding alternative antags to the rotation, but I believe its much-needed. Even zany corp mercs has alternate opponents for the mercenaries to fight.