I'm running Burning Wheel. The group are wizards on the cusp of the fabled third age of magic. I'm using the Trilemma Adventures as well as the setting from the book. I've got seven players so I'm just over the stressful threshold.
It's absolutely awesome.
I'm working on a spherical dungeon. It contains many monster factions that are bound to anchors so they cannot leave their areas. As the players destroy the anchors and beat the factions the strength of the other anchors all increase leading to the factions having access to each other's spaces. The deeper the faction's anchor is beneath the surface the more they benefit from the expansion of their range.