For the lazy:

“That class has to be the Spiritborn. Blizzard hasn’t acknowledged the mistake it made in early October when an internal testing version of the game was updated and made briefly available to former beta testers for Diablo 4’s launch. The few who managed to download it found text in the files that points to the Spiritborn class and its abilities, along with other hints at upcoming features coming to the game.

The leaked build doesn’t paint a full picture of the Spiritborn class, but here’s what we can assume from the text:

Spiritborn will use glaives as weapons Instead of mana or fury, they will use a dual resource system to cast skills The Spiritborn class mechanic will have something to do with “deities” Spiritborn skill names suggest they’ll have a pet or minions of some kind”