Humans and the shorter-lived races occasionally wonder at the rarity of elven heroes. While they may have tart things to say about the elven proclivity towards obscure philosophical debates, few claim that elves are actually incapable of learning, and many wonder that centuries of lifespan don't produce superlative expertise in every elf. Even the thickest tradesman should be expected to become flawlessly expert at his art with three or four or five hundred years to practice it, yet even very aged elves rarely exceed ordinary human levels of skill. Elven warriors are brave and competent soldiers and elven arcanists are gifted with great learning, but they are by no means the superhuman paragons of prowess that a human might expect to be after three hundred years of practice.
The reason for this scarcity is rooted in the cost that expertise demands from the elven mind. Every trick, technique, or experience that an elf preserves in memory is one more thing to be kept balanced in their nightly trances. Nor is it possible for an elf to simply reduce a lesson to its essentials; he must re-experience the full memory to retain it. Once the memory is integrated into the fullness of his identity it is not possible for him to drop it without risking the complete collapse of his identity. He may not even be fully aware of the way in which the memory relates to other portions of his past, and losing it can result in a catastrophic cascade of memory failure, cutting huge portions of his identity loose. Last of all, the maintenance of the memory requires time and attention, both of which are finite quantities. An elf has only so much capacity to remember. Eventually, that capacity will be exceeded and Drift will occur. An elf who collects only his sweetest and most pleasant memories might last for five or six hundred years before the weight of them overwhelms. An elf who attempts to build true mastery of a demanding art is lucky if he lasts three hundred before his identity collapses.
This cost is simply too great for most elves to bear. Not only must a would-be hero accept a lifespan only half that of his peers, but he must accept the retention of grueling, painful memories that he can never abandon as his brethren could. A would-be warrior hero must remember centuries of bloodshed and pain, reliving each night a lifetime's worth of wounds and killing. An aspiring archmage must remember the countless mistakes and missteps on that path, and the sort of torments unique to a mind and body twisted by arcane energies. Human heroes have the blessing of forgetfulness and the ability to distill great suffering into general principles. Elven aspirants have no such luxury, and must relive each night some portion of the suffering they endured to attain their powers.
With this in mind, only a tiny handful of elves ever aspired to be more than respectably competent practitioners of their trades. The vast majority of elvenkind was quite content to live long, golden centuries of peaceful happiness, collecting a thin strand of the most pleasing memories. Collapse and Drift would come to them eventually, but their lives would be happy in a way that other races could scarce hope to experience- every memory a sweet one, every day a vague golden thing falling away with the next day's dawn. It required a particularly focused and perhaps self-destructive sort of mindset to give that up in exchange for the hope of power, but a very few elves in every generation could be found to make that bargain. A few of them even survived their education, becoming "Great Ones" in the most common term.
The consequences of this bargain varied wildly, but they were almost never pleasant. The ever-fresh experience of their memories tended to produce an emotional numbness in the Great Ones and a distance from common feelings. They experienced pain and suffering so often and so intimately that these things often ceased to mean anything to them, and some spiraled into progressively more dramatic madness. Coupled with their legendary prowess, many tales of the Great Ones end with their destruction at the hands of other heroes or their own Creedmates after they lost all ability to deal rationally with other elves. Others self-immolated as even their own continuing existence ceased to be important to them or else became too burdensome to endure. Great Ones were invariably revered as mighty paragons, but they were revered as were earthquakes or typhoons- agents of inexplicable and incomprehensible destruction.
Unlike other natural disasters, however, Great Ones were also capable of creation. Some of the most venerable and honored Creeds were founded by a Great One's philosophical teachings. The arcane workings of sorcerously-inclined Great Ones remain in the House of Peace as ineffable constructs of magic too baffling and abstruse for even the mighty Imperial Arcanists of the Ninefold Celestial Empire to unravel. And while raids on the periphery of the House of Peace have always been a part of life there, every foreign warlord who has ever attempted an actual invasion of the elven homeland has invariably been repulsed with spectacular violence by the forces of a warrior Great One capable of turning elven potters and farmers into an unstoppable legion of death-dealing soldiers.
While most Great Ones die in pursuit of their cause or in conflict with other Great Ones, and most of the rest gutter out into Drift, madness and self-destruction, a very small number among them choose a different fate. Rather than live out the full span of their days they choose ritual suicide in order to preserve their identities for some dire hour of need that their descendants might encounter. By virtue of powerful rituals, these dead Great Ones can be restored to life later in order to check some otherwise unbeatable foe or resolve some crisis. Of course, once a Great One has been raised from the dead, there is no guarantee that they will agree to go quietly back to the grave, and so these Ones Who Wait are rarely disturbed save in desperate need. More than a few have been forgotten entirely as the necessary details of their identity have been lost, and the rituals involved cannot reach them to bring them back. Others have been intentionally forgotten for fear that some reckless savant might call up a past better left dead.
With the coming of the blue crystals and the sundering of elvenkind into True and Immanent, these old ways are sure to change. The Immanent now think and remember much as humans do, and while there is no longer any special penalty for seeking greatness, they can no longer rely on the perfect elven memory to support their learning. The True are still in the grip of the old circumstances. They remain susceptible to the special traits of elven memory and Drift. How the change might affect any Ones Who Wait that are brought back, or whether the split has even affected the elven homeland in the first place… these things remain mysteries at present.