Take Anna for example. She was a formidable figure who could literally extinguish the twins with a single word, and she was just a low-ranked wizard.
Moreover, having delved deeply into the novel of their world, he was aware that there existed many enlightened low-rank wizards of the transcendent type who could easily outmatch the twins. Although the twins were indeed formidable against other types of wizards when they worked in unison, against 'broken' characters—wizards with abilities so profound and unbalanced that they disrupted the typical scales of power—they were merely another obstacle that could be easily overcome.
Valerius was not boasting without merit; he was himself one such 'broken' character, uniquely powerful and more than capable of handling the twins single-handedly.
