The Rahjs are a quartet (at least) of Rakshasas who trade favours for a living. Unlike most Rakshasas, they tend to keep their word (and even the spirtit of their agreements) and do not shapeshift unless they need to. They also seem to have found a way to quantify Karma, which is more than a little odd.
The Rahjs are so far the only entities that use burst divinations. These are a way of casting many divinations over a large area in a short amount of time. This allows for quick acquisition of information, perfect for taking advantage of short periods of time where anti-divination wards are in compromised. The drawback to this, however, is that the divinations come back in riddles and strange codes that take significantly longer to decode than casting divinations back to back normally.
The Rahjs have often referred obliquely to examining the fate matrix of a given entity, but little is clear as to what that actually means. A fate matrix appears to be some combination of fey magic and arcana (or perhaps psionics?) used to gather information about the location and actions of a specific entity in the present/future, mainly the latter. It is also apparent that the Rahjs make these matricies, as opposed to merely being able to discover/analyze them, so they are not a naturally occuring phenomenon. The matrices of different entities can also interact.