I tracked the spawns on this guy and either he, the ph gnoll or the unfabled version was spawning about even 90 seconds with some breaks of ~ 3-5 minutes when I think I was just oor of where he spawned.
I was limited by level 40 druid track distance.
All his spawn locations were in either the southern part of the zone (at most slightly north of Paw). Group of level 46 mage, chanter, merc tank, merc cleric, level 44 druid died fairly quickly.