FYI I uploaded a new version of the render toolkit with the spooky dungeon files in it.
I tweaked the composite render settings to require 99.9 convergence instead of the default 95. It makes the composite renders take a bit longer but it will get rid of the grainy-ness on those images. (If the composite is 90% transparent pixels and it stops rendering when 95% of the pixels have converged, it's really only half rendered)