Been in a kind of a debate with a couple black mages on this.
Here are the facts as I see it, I am not a mage in any way shape or form.
As it is my understanding, Black mages tended to use Thunder IV/Thundaga III on nearly everything because of three factors: It was the highest tier spell, nothing really resists thunder, and it bursts on light.
As it is my understanding, Black mages tended to use Blizzard IV/Blizzaga III on nearly everything else because of four factors: It was the second highest tier spell, nothing really resists Blizzard, It bursts on Distortion, and it had the added bonus of having it's main stat staff come with 10 elemental magic and 5 int.
As it is my understanding, all the spells are pretty much equal now, they all cost the same MP, they take the same time to cast, and they should, in theory, do the same damge, with the exception of one spell, Freeze II.
Freeze II is a no brainer. You can burst it easy on any distortion SC, which most, if not all melee, even the stupid ones, are versed in, on how to open and close. It's got the elemental Staff that has the best stats/bonus for the spell, and will likely garner the best investment.
The second spell however... Is Burst II still King? And if so, it it only so because BLMs merited Thunder potency?
Wouldn't it make more sense at this point to choke up the merited potency and gear more towards what you do with your time? If you're fighting Fire mobs, maybe it would be best to merit Flood II and water potency, I.E. Tiamat. Or perhaps you do a lot of Ouryu fights, maybe Tornado II would be better? Maybe it is a matter of the Light Skillchain, and you need to do the Thunder. But... If you know your LS has a lot of Unmerited BLMS/New Blms, or the opposite, overly merited BLMs, maybe Meriting Flood II would be good to open the lowered resistance to thunder for them.
I mean is there any real though going into your selections? Or is it just "Z0MG THUNDAR LOL!!!"
Hmkiroko had a good plan, and a lot of BLMs I see are basically basing thier choices off the "I merited Thunder/Ice potency already" philosophy.
I mean I know most fights are T.Threnedy'd/Suiton'd for the majority of the time, if not I.Threnedy'd/Huton'd for Blizz.
I was just more curious in hearign more peoples' voices on this subject.