Jaws of Death
The second that Rui found a way to adaptively evolve to Master Brigsby's pesky tactical support, the other Masters experienced a deep terror in their bones.
They felt a blood-curdling peril emerge from Rui that made them swallow.
Nothing about him had changed before.
Neither his power level nor his effective combat strength.
What changed was their own evaluation of him, which generated immense fear from the depths of their heart.
The barrier of protection that was protecting them from defeat, Master Brigsby's powerful tactical support, had now been stripped away, leaving them to deal with the monster before them unaided.
It was like how humans could relax in the zoo with the knowledge that the reinforced glass was very much able to protect them from the powerful animals caged within.