Nice. I beat the overlord with a Blood Giver.
I had the flash heal upgrade that made free spells better as well as the blood transfer upgrades that makes it better at full health and restores your health if you kill something with it, hitting for insane damage and killing enemies in 2 or 3 casts.
The new models are nice but I notices some animations don't loop properly.
The new intro is cool too, but I'd like an option to skip the tutorial.
The new crit effect is good, much more noticeable.
You should be able to open the spellbook when levelling up.
The shop currency icon blocks mouse inputs, making it tricky to click the item/spells/refund buttons when at the shop.
The level up menu also reveals the "cost, total" UI that shows up when you mouse over a purchasable item.
Did you make cromwell harder? I don't mind it but I'd say that he's the hardest boss mechanically because aura of agony is a DPS check on an enemy that can heal itself, I can see beginners getting potentially overwhelmed with it.
The arcane magistrate is only a matter of dodging damage zones so it might be a better suit for a first boss.
Very fun overall, can't wait to play the new areas too.