Occultist has a ton of one point wonders (pets automatically scale with level), aswell as having a large variety of abilities (even an autoattack damage boost, Solael's Witchfire), making it one of the best classes to either major in, or to branch into. Curse of Fraility lets you kite even the fastest of mobs, while also dropping their defenses significantly. Bloody Pox is absolute shit until you pour a ton of points into it, but after putting a bunch of points in it is a great boss killer. Early on, the best sustain comes from your Raven's Mend Flesh, but later on Sigil of Consumption can really FUCK SHIT UP (hint: putting points in the sigil itself doesn't raise the damage by much, instead, later on in the path Destruction gives it a ton of damage, which in turn gives you better health drain). Tie the eye's special ability with Dreeg's Eye for twice the eyes.

My favorite build with occultist consists of focusing initially on Dreegs Eye (don't get the passive ability that increases damage and cooldown, it's better to spam it, trust me), then using the points you get from purifying altars to spec into the god, Eye. Occultist: Easily the most powerful class in the entire game, they've got everything, strong sustain, decent damage, CC, pets (raven has a heal/stun/lightning damage buff, demon dog is a decent tank)

Grim dawn best class combo