there have been some great posts on settlement magic and combat mechanics already, so i won't repeat anyone here.
personally though, i wonder what specialist slots are and whether the game needs them. personally i believe this game has tow many reesources already. i personally don't really see the need for crystal and elementium to be separate resources but that's just me.
question in point: if mana maintenance is coming in for spells, then will enchantment slots remain also? aren't they sort of the same thing also? if they are a "perk" for levelling characters that could be something i suppose. if they are a settlement thing (ie you either build this building here or this one) then i don't like that so much. i think it overcomplicates things. i think the game will work better if players only have one or two developed settlements and then small farming/mining villages on the peripheries, and this will just encourage lots of big cities.
What we want to do with specialists is use them to reduce the # of resources in the game.
Basically, the concept comes from our other game that's in long-term development called Society. In Society, the core mechanic is what do you do with your people. Your people are the key resource and what you do with them determines the fate of your society.
In Elemental, we had intended to have people as a resource but it didn't work out so well in a TBS (Society is RT) and specialists allow us to abstract it.
Let me walk you through it so you can see what I mean:
Once upon a time in Elemental BETA 1...
Your Kingdom rose and fell based on the decisions you made with your cities. You could build multiple merchants, studies, etc. In this way, a player was inclined to only build a few huge cities and the AI was designed around this.
However, in time, it became untenable because we couldn't cap any of this because, at the time, the game engine wasn't as flexible as it is today. So users ended up making 1000 gold per turn and 1000 research per turn. When I'm making AI and game mechanics, I work with what I've got and thought I had found a satisfactory work around for the limitations -- only 1 of these buildings per city. Of course, that didn't work because players would just build multiple cities. So then we made cities have an administrative cost. But then it just slowed down the game so we started putting in maint. cost on some buildings but not on the early ones (like merchants). But that didn't work because as long as you can get something for nothing (a merchant in v1.0) there's an incentive to crank out lots of cities which corrupts the balance.
Now, fast forward to now. Now it's relatively easy to add new types of resources and I can get in the concept of specialists which are essentially your population -- every 10th citizen can be a specialist which you can then be used to have a merchant (instead of using food) or a study (instead of it costing gold) and so on. Right now, the ONLY resource I have to work with that doesn't "store" per turn is food which is too limiting. As a result, you end up using food, materials, metal, and lots of other resources in weird ways to try to achieve balance.