So yeah. These augments are random as hell.
Each stone seems to have it's own pool of augments. It'll give you between 1-6 random augments, but they will all follow a particular path that you chose at the start. You can pick melee, ranged, magic or familiar. Seems like the dusk type stones give attributes frequently, the snow type seem to give better atk/acc/mab/ect. The leaf type don't have any pattern I could recognize.
We only dumped about 40 stones apiece into each piece of gear, and the only thing we really noticed is that EVERYTHING IS INCREDIBLY RANDOM. You don't get to pick what augments you want to keep from a particular set like you do with Alluvion, so it's more like the original skirmish. And as you can tell, they are indeed worthwhile. Didn't bother trying any melee/ranged/magic, so no idea what is possible from those.
Another thing to note is that several of these NMs are hard as hell. We only fought them once each, and the first three we fought with three people, didn't go so well. We didn't lose to anything after we had a full party. They start at level 129, and they probably are not at all PUG friendly. Most of them have stupid gimmicks are cheap moves. A good example is a Mimic that stuns everyone for about ten seconds as soon as they spawn while applying a very powerful poison to everyone. Or the tonberry team that split off and attacked people randomly right after they zerged the popper.
This content was designed to keep people busy for a long time.