Skade said:6 12th level characters is a bit powerful for that unless you make teh encounter someplace interesting, like say near a cliff or some other natural danger so that they might be dropped really far. If the monkeys are using weapons give them bolas and nets, things that would help them pin someone and then lift. Falling damage is nasty, and even a monk can't use his falling thingy if he is pinned.
I gotta get to bed. I am only barely coherent at this point. Have a better day at work, OK?