The idea is simple at its core, but given that it's a big change, I don't think it'll happen until at least AVWW 3.0. But heck, who knows, you might be inspired!
The core of the idea: Remove mana! Simple, yes? Of course, other changes will have to happen in order to facilitate it, so the post won't end here.
So, why should this happen? For one, it will make balancing spells far far easier without the limited-yet-unlimited resource that mana is today (which is compounded even further with the preserving mind enchantment). In addition, it will allow for further specialisations for characters (right now, I completely ignore mana upgrades; heck, I play with a character with 40 max mana right now).
Of course, there are things that do rely on max mana or mana regeneration at the moment, most notably storm dash, shields and some high-powered spells. I'll go through these point-by-point.
- Storm Dash: Frankly, I don't see a need to fix this. Let people storm dash without any kind of limit if they want to; they already can with enough tiers in Storm Dash anyway. Suggested changes to tiers: Increased speed and/or decreased damage increase.
- Shields: Yeah, this is the only one I haven't managed to come to a conclusion on. Suggestions include: Change elemental weaknesses/resistances (fire shield would give 50% resistance to fire and 50% extra damage from water etc), or limit them in duration (a shield can only be up for ten seconds before needing to be turned off).
- High-powered spells: This one is actually really easy to fix: Change the requirement to magic power instead. Need to cast meteor? You'd better have a magic power of at least 130%.
With the removal of mana, there's the problem of suddenly only having two stats to increase. It's easy enough to add a third though; just re-introduce casting speed in the form of magic control. This would work exactly like the current cooldown enchantments. It would also add in another condition for limiting spells (and even combination-limiters; for instance, the meteor shower spell could require both a high magic control and a high magic power).
Now, I'm sure I've missed some other things that need fixing, but that's what the forums are for!