I can't seem to turn in either quests(Mammoth Calf Hides, Gnoll Fur.) I'm apprehensive with the faction, according to allakhazam posts they should be taking the quest items and just giving faction back for it. When I hand them the items, they simply give them back. No "I don't need this" text, just handed them back. I tried the invis trick, same result. Thought it might have been fixed so I tried sneaking and turning them in(do you have any idea how long it takes to get a successful sneak at level 10 on a ranger?), same result. Am I missing something? If it has any impact, I'm on Rizlona TLP but I know these quests were available at least sometime before Luclin launched.
Try getting a friendly enchanter to come to the zone with you & cast illusion barbarian on you prior to attempting, the faction level required may be wrong on ZAM for non-Barbarians.
Apprehensive faction may not be good enough. If you were a barbarian of the same class and deity persuasion, your faction would be much higher than that. There are also gradations within cons. It may say it requires apprehensive on Zam, but it may be a higher numerical value of apprehensive than you currently have. You might have to kill a bunch of nuisance mobs that that guild hates to get it up enough to do the turn in. Edit: OK, I just checked. Those quests require you to be indifferent, not apprehensive. Unfortunately, there's no way to increase Rogues of the White Rose faction apart from their line of quests, which you can't complete at apprehensive. They have no opposing faction that you can go kill to increase it. I think you're going to be out of luck.
Keep hitting sneak until the quest turn in npc cons indifferent from behind. Hand in item and have someone else grouped with you cast invisibility before you hit the give button. Some races that have rangers also have hide as a skill, not the same as a rogue since it will drop the hide if you move.
