I finished the game in offline mode in approximately 15 hours as a caster with staff.
What I can share in terms of my experience is that it can be difficult going solo as mage as they seem weaker than melee toons so expect long fights.

Do not invest all your points in to ferocity and ignore toughness. I pretty much went mostly scholar on the tree and right in to the explosive meteor side of the wheel. Finished on level 41 and only had to repeat twice the Act 3 final boss. I think story mode is easier than normal though.

I think I used anomaly, light bringer, winters grasp, burning embers and the aether teleport almost exclusively. Pretty much full AoE.

I really enjoyed the play through it just feels like a real slog chipping away at enemies that can one shot you.

I'm online, hopin to get some help as well, thanks!

atleast when the servers don't die

from 1 - 15 would just stick with staff attack.
all points into agility and go for projectiles nodes.

https://wolcen-universe.com/builds/y8YQQO-1-15-low-level-staff-mage

From level 15 u could respec and go pure Ailment. Or just level aliment from the start.

https://wolcen-universe.com/builds/gkRxJG-ailment-lvl-22

big nodes info:

Grievous Afflictions. 2 different aliments from 1 hit. So if u use Lightning Strike and press "S" the 2 biggest damage source are gonna be the aliments it will do.

Good skills to get.
Livor Mortis. insane tank minion
Bulwark of Dawn. nice heal, and with the right skill modifier it also do good dmg.