Regulator

A regulator is a small device that is worn on the head by many Alexandrians and forms a central part of their society. Their usage is optional but many choose to wear them.

An electrope device issued to citizens of Alexandria, the regulator boasts various remarkable capabilities. Chief among them is the ability to resurrect the wearer by imbuing them with life force extracted from other souls in the event of unanticipated death. This has allowed the people to live out the span of their natural lives, provided they have sufficient surplus souls. By way of a similar mechanism, souls can also be harnessed to temporarily enhance one's physical prowess, this usage being common among those in dangerous occupations such as soldiers, hunters, and arena fighters.
Additionally, regulators have the ability to manipulate the wearer's memories, a function that served twofold purposes: to remove all memories pertaining to death, thereby sparing Alexandrians the fear of mortality, and to preserve the memories of the departed as data. This data would thence be used in the creation of an Endless version of the individual.
Such a powerful and ubiquitous device, however, could be misused by those with influence. This was made evident with the neo regulators, whose adoption Calyx encouraged by having the simulant, an impostor of the fallen Queen of Reason, declare that only their wearers could become Endless. By concurrently limiting the device's availability, Calyx cultivated heightened terror towards death among the populace─terror which he exploited to manifest the dread primal Necron.
Following Calyx's defeat, the government of Alexandria took steps to unlock the memories of the departed within citizens who so desired. What regulators have taken away, regulators shall restore.

— Unending Codex: Regulator

Regulators, as the name suggests, regulate the wearer's reserve of souls. Should they die, the regulator expends a soul to bring them back to life. The regulators are constantly recording the memories of their wearer, so if they should suddenly die, their memories can be refreshed as part of the restoration process. This is how they preserve one's identity and sense of self. When a person dies of natural causes, their soul is temporarily housed within the regulator. It's then delivered to a facility where memories are separated from the soul. The result is a fresh soul cell, free of impurities, ready for distribution and consumption.^[1]

Regulators can be loaded with two kinds of souls, those of peoples and those of beasts. The souls of people can be used to grant the user preternatural strength. Naturally, they can also be used to ensure no one suffers an untimely death. As for the souls of beasts, they work much in the same fashion, imbuing you with the strength of the chosen animal. If, for example, you used the soul of a wolf, you would grow more agile and feral. Using several of the same type at once, however, would result in physical changes. Your teeth might become fangs, your nails claws—too many, and you'll become more beast than man.^[1]

Souls are packaged in cells, and they can be used to replenish the life force that is lost due to sudden death, such as in accidents. They do nothing for those who die of old age, though. Distribution of soul cells is based on one's work evaluation. To encourage “exemplary performance” when fulfilling their duties.^[1]

Like the barrier encasing Alexandria, this system was created to overcome the calamity that transformed the world hundreds of years ago. Amidst the mounting death toll, scientists used electrope to devise a means to save what lives they could so that the nation could endure.^[1]