[Echizen777]

Originally Posted by XFire

That only applies if Tats is restricted. Gram Dispersion would take Rupture out of play, and Masaki has no equivalent counter for Mist Dispersion.

The quote said without restricitons

Spoiler for QUOTE:

Even if this wasn't a competition and live battle instead, with both
sides going all out without restrains, Tatsuya had no confidence that he
could "triumph" over the two of them at the same time, nay even if he
was against Ichijou Masaki alone.
"Under a state of restricted power and ability ...... for one who belongs
to the side that restricts such as myself, to go and say such a thing is
illogical, and may arouse your displeasure, but......"

Justly Tatsuya was worried because he couldn't win without an excellent plan with his restrictions. Contrarily to our protagonits the OP side characters have less occasion to show their strength but even with what he shown I don't see how he is not a match for Tatsuya.

His Rupture is the only spell faster than Regrowth, Kyokan Jigoku would be useless.
His weakened shots could knock out everybody but Leo, he is good at bombardment, his Armor of Interference is like a mini Phalanx(Tatsuya could bypass it with Trident though). Even if Tatsuya can counter all his attacks, he has been hurt several times in the story. It's not as if they will stand still during a fight to death and both are soldiers trained for combat.