Pale master was a popular prestige class back on 3/3.5e times, sadly, the class was SEVERELY nerfed on Both neverwinter nights games(not confuse with the wow clone mmo), you need to use spell fixes(2) and PRC(1) to have a faithful adaptation of that class. But Larian can do better than previous games.

On 5e, the prestige class got ported into a "class" since there aren't prestige classes on 5e.

https://www.5esrd.com/classes/3rd-party-publisher-classes/grimlore-entertainment/the-pale-master/

https://www.dmsguild.com/product/242532/Deathseer-Pale-Master--Vicar-Fantasy-Grounds-Class-Pack

Originally Posted by "5e SRD"
The Pale Master is a magic user obsessed with the study of life and death. They specialize in spells and incantations that allow them to harness the very life-force that flows through all creatures. Where a life-force is not present, they are able to instill a mimicry of foul life, rising these dead creatures from their once peaceful earthen resting places.

Of course, since it isn't PHB, It should only come AFTER the game is ready.