True Names

Across the vast, differing worlds that make up Thel, there are few multiversal laws. True Names are just one of these. Every living creature in all the cosmos has a True Name, a unique Word of Creation that refers to the soul of a creature. Creatures that lack a soul, such as Constructs or the Undead, do not have a True Name.
Invoking the True Name of a creature grants the invoker complete and utter control of the individual. Any command that refers to a creature by their true name cannot be resisted by the creature, and it forces them to carry it out to the letter. Like all Words of Creation, however, the discovery of a True Name weighs heavy upon a creatures mind, and they are subject to the same limitations. Attempting to learn too many True Names, or invoking a True Name too frequently, can lead to the destruction of the invoker's mind, leaving them a burned out husk.
However, a creature that discovers their own True Name can become one of the most powerful creatures in existence. The first time a creature invokes their own True Name, they are blessed with a phenomenal cosmic power. Such powers can be taxing on mere mortals, and thus the power granted must be nurtured before it can be wielded freely. A creature with the knowledge of their own True Name is still at risk of another creature abusing it, however. It is possible for powerful creatures to curse the knowledge of their True Name, causing any creature that discovered it to transform into an Allip.

Mechanics

Any creature that learns and invokes their own True Name gains an epic boon from among the options in chapter 7 of the Dungeon Master's Guide.

Type

Metaphysical, Astral