Something my raid team noticed awhile back When the Ogres touch the wall behind where they spawn they will instantly teleport. This is typically caused by grenades that don't attach which trigger the retreat mechanic of the Ogre in an attempt to recede from the oncoming avoidable damage (ex. Solar grenade). Seriously, try it. Once they touch that wall, it's all over As to why touching a wall triggers a teleport? Clueless. Maybe Bungie was too afraid of a reoccurring Atheon situation.