Because of N.O.X.'s high level, this deals much more damage than listed, upwards of 500 on a 60 AL target.
Before N.O.X. uses this skill, he will use Countdown. N.O.X.ion Buster is uninterruptible until the countdown is finished. A chat bubble will appear over N.O.X.'s head, showing how many seconds are left in the countdown.
N.O.X.ion Buster can, however, be disabled during the countdown, causing the skill to fail.