So far, the combat works well, but it's a bit bland if I'm honest. With how sparse the enemies are I have the impression you want each encounter having it's weight instead of Diablo's slaughterfest but it's not really present at the moment. Being able to see enemy silhouettes through the fog of war is also pretty OP at the moment as with a ranged characters you can easily kill them before they are even able to get into your range of vision.
Some starting money or a way to select your starting equipment would be nice, as one run I started specing into spells but only found a wand at level 3 and had to make due with a bow until then.
Speaking of spells, right now I didn't really felt the need to upgrade them apart from Lightning bolt, as that was the only one that increased damage. Projectile speed doesn't really matter with how slow everything moves, and AOE felt unnecessary with how sparse the enemies are.
Stats seem fairly straightforward of what they do, though it feels like the point system is way too granular for the effects they give. Many times I had to dump 5 or so points into a stat before I saw a miniscule effect. Cutting down so you have less points to spend but each spending is meaningful might be better - at any rate, could be would be worth experimenting with.
Some kind of indicator on the main screen when you level up and have points to spend would be nice too. Many times I only realized I have points to spend after levleing up 3 or more times already.
Support/passive skills are also a bit confusing. The UI mentioned cost for them to cast but I wasn't able to draw them to the quickslot bar.
As for the quickslot bar, it would be nice if you could reorder already existing items there, so if you want to move something you don't have to delete and find it again in your skill book/inventory.
Still, for all it's faults a solid prototype so far.