Masteries
These are rare, high level abilities that characters obtain by influencing the world and the people within it in a way that justifies a power boost. This is not intermediate magic (poison, bone, magma, sand, etc), which can be taught in-game or learned with consistent play. This tier of power has higher quality expectations and is seen as a reward for good play. This might mean a well written in-game journal, or an approved application in the ability section of the forums.
Characters with a master ability already are less likely to progress beyond that point.