BLM on frontlines is really lacklusting now since Frontlines are about pushing and retreating fast. Same goes for Rival Wings, they're great to kill Machina and Mammets though. BLM burst in PvP is dependant on Thunder, gotta apply it, Fire IV twice to get the Thunder III ready. To move just keep alternating from Fire/Blizzard to keep enochian and buffs rolling and deal damage.