The Peacemaking is of no help really, aside from maybe a minor buff to Despair, the Discord Mastery.
You should be able to do Doom no problem.
Neira no problem.
Serrado no problem.
All Ilshenar spawns done at Valor no problem. (Becaue of all the handy nearby Greater Dragons and Greater Dragon Parragons there are to Provoke.)
Giant Turkeys no problem.
Harbingers no problem.
2x of any normal monster even parragon versions of, no problem, like Cu's, Greater Dragons, Ancient Wyrms.
The Weald, Bedlam and Labyrinth spawns are probably a bit too slow to level with it, but could be wrong, haven't tried since Mastery's were added.
Shimmering used to be possible but they fixed it.
Mostly agree with Poo, depends on the player more than anything.