Random gear being more generic stuff (Like BG3's regular "+1" and "+2" gear with no fancy unique effects) that you can use to fill out your slots while you run around bumping into the fixed stuff that has more bonuses for specific builds.
Also having fixed gear having multiple potential spawn locations would be interesting.
Outside of that, something to consider would be some sort of crafting system where you could build your own items, utilising effects you've previously found.
You mean sometimes enemies drop +0 and sometimes +1 and +2 weapons? I wouldn't mind it but i don't think it would make a huge impact in terms of gameplay, maybe slightly more/less damage or defence sometimes but that's it right?
I think the majority of the people who rerun the game propably plan out builds and want it to come online asap. If there is x amount of locations where you could get one of your core pieces, I would rather find it annoying, since i want to play with my build as much as possible. Crafting could be an option, but it also requires to be balanced correctly with multiple copies of an item, which is a worry i have.
I think the best way to handle surfaces is to put them onto specific skills.
Yeah I would agree with that. Not every spell needs to create a surface as a side effect. Maybe 3 or so per element i don't know (also depends on the cooldowns). And you still have dedicated spells that only create a surface like rain/blood rain.
For me, the main thing I want, is more emphasis on LIGHT.
More light impact would also be nice, maybe day and night cycle as well. I felt like even in the shadow cursed lands you didn't have a huge disadvantage without dark vision or a closely located light source. Range is a big thing too - in bg3 combat areas tend to be smaller than in dos2, so you would almost never have much issue hitting the target as a mage with your spells. That could be something to consider as well.
Also, would love to see movement be divested from AP. At least having a baseline movement capacity independent of AP, with optional "Sprint" style consumption of AP for further movement (As well as an AP sink for disengaging from targets). So there's more freedom to use positioning, as opposed to Original Sin where you just sat there like turrets because spending AP on attacking > spending AP on moving (Not to mention how this also neutered enemies, who'd waste all their AP running at you instead of attacking)
Yeah the movement beeing tied to AP is a bid odd but i can see it as a balancing tool. It is a bit tricky, on one hand i would like to chain a lot of skills to get out cool effects and on the other hand i don't want to burst down the enemy. I think I would also not want to see kills, that just give you more AP (basically beeing the Pot of Greed of Divinity). You where able to get to ridicoulos levels with adrenaline+flesh sacrifice+skin graft to reset those cooldowns again and gain even more AP. At that point every fight becomes redundant.
I also forgot to mention that i would love vertical targeting like using a skill underneath or above you. I saw that on Solasta 2 and thought it was a really need idea to use skills.