From publisher blurb:
A Prestige Class for 5E from the Realm Scribe!
The death knight is made when paladin falls before fulfilling their oath and makes a pact with a powerful being to get a second chance, or when a warlock in service of the forces of death swears an oath that gives them power beyond their patron. They are transformed into an undead creature, but left with their own mind and will. They can use the power of their patron to make their very presence spread disease, encase themselves in protective ice, and fill their own servants with the draining power of undeath.
This class is for high-level campaigns that allow for multi-classing in order for a character to meet the requirements for this Prestige Class. It is designed to fuse together the idea of a bound warlock and an oathsown paladin into a champion of undeath, and requires high charmisa and strength, levels in both the paladin and warlock classes, and to be at least 10th level before taking a level in this class. Prestige Classes are very powerful and meant for high threat campaigns.