It searches through the banlist for a banmask containing the host of $2 (a nickname)

Author: Rolo @ #mIRC on Purplesurge

on *:text:!unban &:#:{
  if ($nick isop #) || ($nick ishop #) {
    whois $2
    set %nicklookup $2
    set %chanlookup #
    mode # b
  }
}
raw 311:*: if ($2 == %nicklookup) {
  set %hostlookup $+($2,!,$3,@,$4)
  var %x 1
  while ($ibl(%chanlookup,0) >= %x) {
    if ($ibl(%chanlookup,%x) iswm %hostlookup) {
      mode %chanlookup -b $ibl(%chanlookup,%x)
    }
    inc %x
  }
  unset %*lookup
}