[Echizen777]

Originally Posted by SoboSobo

I guess it depends in what area the BS is specialized. For tatsuya for example he has more then one spell.
His trident contains 3 different spells wrapped up in one activation sequence,that includes mist dispersal.
Gram dispersion is another spell, area-of-effect decomposition is another(its mentioned in volume 12 ch1 but the way its mentioned seems he know this for some time), material burst is another. I see at least 5 spells so far.
I true that Haruka seems to have only cloaking, but the author hasn't actually shown her true abilities, she might have more then cloaking.

Surely it depends but I don't see why you'd think Haruka can do more, maybe she has other variety of cloaking but that's everything I can imagine. Tatsuya can only do 2 things

Spoiler for Quote from V08:

"From the time he was born, Tatsuya could use only two types of ‘magic’.
Decomposition of Eidos, and reconstruction of Information Bodies. Within the
concept of these two categories Tatsuya has devised a variety of techniques
he can use, but however far you take them, with just those two, it is
impossible to alter Information Bodies as a true magician should."

He created varied techniques but they are still essentially Decompostion or Reconstruction.

As for tatsuya not knowing ZI and DF its wrong, he knows them but because they fall in the generalized magic category he can`t use them very well.
We know ZI is very dependent to the user interference strength which Tatsuya has plenty of it(stated the reason he and lina was able to use spell under miyuki heavy ZI was because their interference strength was higher then the ZI).
Interference strength= the ability of the magician to change the eidos, giving that tatsuya can even tap into its structure core that alone gives him an insane amount of interference strength.
But ZI its still a spell that needs recasting, and with tastuya cast speeds in general magic being very shitty this spell its not that useful in a battle.
Besides who needs ZI when he can use AOE decomposition spell to act as a shield around him(is this aoe spell gram dispersion used as an area of effect spell by any chance?)

DF and ZI are common counter magics but it doesn't mean everyone use them, some magicians have their specialized counter magics.

Using IS and ZI are completely different things. ZI creates a fixed area where magic is nullified and there is pure interference strength, like during the clash between Miyuki and Lina in V9, here Lina could do nothing, that was Miyuki's full and pure IS. Masaki for example used a large wave of IS to erase the phantoms, that's not ZI.

So far, Miyuki is portrayed as the magician with the strongest IS and her ZI is one of the best in the world. Miyuki's ZI nullifies all magic attacks but hers, meaning that she doesn't use her full IS, otherwise she wouldn't be able to use other magics. If she uses it a full power, it would truly become a zone without any magic.

So, there is a minimum, a minimum of IS you must be able to provide and then struggle hard to maintain it within her ZI and that level is not obligatorily A class since even Tatsuya can do it, if you can't struggle then it's over for you. Tatsuya honed his skills to perfection, he sure is skilled at using his IS, it is not powerful but as he proved against Tomitsuka, he is skilled at acceleration magic too even if it is C-class unlike.

He can struggle to maintain his magic for sure. But of course if he wanted he could have destroyed her zone with Gram spells .