A note in Lord of the Rings Online's patcher hints that Troll and Ranger session play has been disabled, yet again. Sure enough, a post in the forums confirms the situation, so these giants of PvMP are unavailable once more. There isn't any explanation readily given, but looking at the Monster Play forums, a thread can be found with a response from a Turbine official in the first page: "An exploit was discovered that enabled sessions to be nearly limitless. It was decided that the sessions should be shut down."
Troll and Ranger session play has been taken out before, and another time after that. The second time they were disabled was actually due the exact same reason that they are now, which leaves you to wonder whether people had managed to continue the old exploit somehow, or whether there's an all new way to rip off the system. The best thing about the see-sawing status of PvMP session play is that I get to keep using my troll doll picture.