I'm starting to work with another GM to plan out a dual-GM planescape game for our group (about 9 people). Looking through the DMG it looks like we have a good start for a Planescape game there, but there are still more things to take care of such as faction feats and special rules for the planes and planar skills.
I'm curious what additions/changes people here might suggest for a 5th ed Planescape game, either pre or post faction war.
One thing I'm going to do is try and work up a list of faction feats. None required to be in a faction but feats that require a faction to obtain to reflect the special training and benefits of factionhood.