There are at least 20 things I could post about more interesting than my checking parameters for black magic spells (BG forum), but those other things would take too long.
That Breakga appears to last only 30 seconds unresisted is notable since the recast time is 50% longer (45 seconds). Compare this to single-target Break (30 second duration, 30 second recast). Even Horde Lullaby II lasts 60 seconds (with only a 24-second recast).
Comet's direct damage/MP efficiency doesn't compare favorably to Blizzaja and Thunder IV without the usual ice or lightning potency merits.
I also checked the magnitude of Kaustra's direct damage, but surprisingly the direct damage appears to be variable in a way that can't be explained by resists. With 85 INT on SCH95/MNK1 I managed to get 378 damage 3 times and 340 twice.