Hussar
Legend
I would point you to This Thread for other possibilities regarding your problems with CR. There could be any number of factors that have caused you difficulties, up to and including overpowered encounters.
Doug McCrae said:I guess they expect the PCs to be non-core. I've noticed this with the monsters in the new books, MM3 and MM4, they're a lot more powerful than the ones in the MM at the same CR. Took me a bit of getting used to. I forgot and put the party at 5th level up against a CR8 MM3 encounter last session which was a bit too tough though there were no deaths fortunately.
What monsters were they and what were their CRs and ACs? Also, what were the level ranges?Retreater said:monsters that can only be hit on a Natural 20 by the party's fighter (who is within the suggested level range for the module)

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.