All holocrons are based on a complex yet elegant technology: a lattice of organic crystals woven together at a microscopic level. The crystal lattice can store vast amounts of information, as well as replicate the appearance and personality of the holocron's creator as a gatekeeper who will guide students in their training.
In his youth, Valkorion--then known as Tenebrae--discovered a way to twist and pervert the lattice so it could capture the spirit of powerful Force users, locking them in a metaphysical cage. He used the weapon on Dramath, his tyrannical father, and trapped him inside the holocron for centuries.
But the same corrupted technology Valkorion used to vanquish his father could also be turned against him, permanently imprisoning his immortal spirit... or obliterating it from existence.