__NOWYSIWYG__[[Category: achievements]] Ghostos replace Ironos during Halloween. The Ghosto boss is only encountered on Wave 88. This achievement can be gained on any map, with the exception of Gridlock, which does not have a Ghosto (Irono) boss. The Ghosto boss will disappear if he destroys an orb, so it does not count as kill. This achievement used to be for members only. This was changed on the 3rd of November 2009. This achievement can only be earned during the Halloween holiday.