Once Arata gets his magic working, he one-shots a dragon monster that was giving five of Trinity Seven some difficulty.
Mira can reflect any spell. Including Anti-Magic. Both times a Magic King Candidate has seen her fire her White Universe spell, they go Oh, Crap!.
Hijiri takes on all of Trinity Seven at once, and would have killed them all if not for Arata.
Hijiri's motivation for fighting in the first place counts as well. After being broken down by Breakdown Phenomenon, she entered an otherworldly realm where she observed Arata and the Trinity Seven destroy the world repeatedly. She is absolutely enraged.... AT THE WORLD. She goes Yandere in the most epic way possible, declaring war against reality itself for daring to use her beloved as a tool of destruction.
Liselotte's first appearance gives Arata and the others a lot of trouble, and they barely fight to a draw. She later attempts to take on the headmaster, but compared to her earlier fight, the headmaster not only manages to dispel her attacks rather easily, he even gives her lessons on how to be a more powerful mage, such as having a grimoire if you're going to fight someone stronger than you. He could easily deliver a Curb-Stomp Battle to her if he chose to. But instead he takes a Helping Would Be Killstealing approach to let Arata gain more experience fighting Liselotte himself.
