[Rava]

Originally Posted by Klashikari

Okay, time to go first:

So my question is: what does he need to do to actually disrupt the spell activation? Does he just need to gaze without any actual interaction? He certainly remained motionless when Blanche leader casted his spell.
[...]

Clarifying the bolded part since that wasn't directly answered.

Spoiler:

Remember how at the end of Episode 1, everything turned blue and the Activation Sequence seemed to be going slower visually? That's the passive part of an ability he has. Said ability is what lets him read Activation Sequences.

That ability allows him to "see" the Activation Sequence without actually looking at the device physically. So he's immune to any visual misdirection that's intended to hide spellcasting, and can pretend to be mislead.