We currently use this for some event monsters. The monsters wander around the map at random. You can hit them, taunt them, or do whatever you want and they will ignore you. We currently use them in our events so that they wander around randomly and are un-killable but they have guard units which contain loot. This way the races can fight over the area to get the loot from the guarding monsters and the main event monster will randomly wander causing an advantage to each race at random.