I know im not saying anything you dont already know, but that guy was a fool Luna. BLM isnt the best AoE class, but its a very respectable one. Fire 2 and Flare are great AoE spells, Bliz 2 is... an aoe spell as well... and freeze... exists. And considering that most default enemy groups are 3 enemies, a non-buffed Fire 2 would be 300 total potency spread between them, while a Fire 1 would be only 180 potency on one of them. To me, that seems like a pretty clear indication of what you should do(aside from avoid people like that).