A lot of people have done a lot better on this topic than me, but here are a few of my thoughts nonetheless.
First off, the essence system is ridiculous. It's clunky, awkward and makes very little sense. Essence is the sovereign's life force, he shouldn't go spending it on very small things. It do like the whole "spend essence to fertilise the land" thing, but I think it is very, very poor at the moment. It penalises mages, as they can't fertilise land without destroying their combat abilities. There are two options for this that I can see, and I'll be demonstrating both of them in a bit.
Also, spell points is a confusing term. I thought I was going to cast magic using that, and only change the land / make super characters and all that stuff using essence. Make it "Spell research points" or something.
Now, there're two options for the "mana" system in this game that I can see as a way forwards.
The first is that essence that we currently see is the player's essence cap. It's what we can put points into in order to increase the cap. Players can cast the usual spells, taking a small amount of the essence but not reducing the maximum. This would be things like fireballs etc. The maximum essence can only be reduced through the player investing in fertile land, in other magic users, summons etc. However, this does NOT reduce the "cap" of the essence, merely my current possible total. So, let's say I fertilise some land (-3 max essence) and cast a fireball (-2 essence), then my current essence would be 10/12/15 (current essence/current max essence/essence cap).
A player could get his max essence back up to the cap by absorbing other sovereigns or channelers or their summons, or by absorbing fertile lands. (Making them wastelands again.) It'd be an investment system in terms of fertile land (you put three in, you can get three out at a later date), and it'd allow aggressive sovereigns to start to field armies of summons if they do well.
The second option is to pretty much completely delink the mana system from essence, and instead use a system similar (ie. pretty much exactly the same except effected by willpower in terms of regeneration) to the current spell points system. Spell research should probably only be done through the magic research tree (researching it opens up the magic, you use that magic to unlock better spells in a system similar to The Elder Scrolls games, using it makes it better). Essence should only be used to fertilise the land, summon minions etc similar to what lowers the max essence in the previous idea. It could be possible to integrate that idea into this, to be honest, but it might be a bit awkward. Essentially, this would be a pure mana system, instead of the current essence one.
Both of these would reduce any annoyance in the current system. But, as I've said, others have suggested better systems than me.
Shards are, currently, rather pathetic. I'm guessing there won't be one of each of them as there was in the last build, because that was just silly and there appear to be magics for multiple shards in the current version.
They shouldn't be just another form of resource, they should be far more than that. They should be things that can change the balance of a game if used correctly. They're plugged sources of raw elemental power, and we just build cities over them? Hell no.
In my opinion, players should be able to build a structure (magic tower or something) over a shard with a pioneer, or integrate it into a city. The sovereign should siphon power off from it (in terms of essence / spell points / whatever system is going to be in place), with a bonus if the sovereign has the appropriate spell book. That's all fair and simple.
However, using a shard should have a few effects. Just building a tower over one (with a city or not) should apply a city or three tile wide effect, which would effect any combat there. Air makes windy gales (making ranged weapons useless?), fire turns the terrain to desert, earth causes tremors in combat and water would make fog, disguising movements on both sides of the conflict. All shards should probably reduce the effect of any "opposite" magic (ie. fire cancels out water) whilst increasing it's own. This could be represented with a "shimmer" over the appropriate terrain.
Sovereigns with the appropriate spell book can, though, "open up" the shard. They are, essentially, allowing more of the power of the node into the world so they can siphon it off. This should have disastrous consequences on the area surrounding it. Fire would create rivers of lava, water would turn it into sea (with shore on both sides), air would do something I really don't know and earth would turn the surrounding terrain (except for a small path in) into mountains maybe. This should destroy the city or a few tiles surrounding the shard. It should probably be able to be done both remotely and without it's owners consent, if the sovereign is strong enough.
It'd add an interesting (to me at the least) strategic element to the game, as non-magic sovereigns will still want to defend the nodes (to stop others from getting more powerful from them) but it's possible for them to effect them negatively etc etc. It'd also give a massive feeling of strength, as you cast "Unlock Shard" and destroy your opponent's city whilst giving them an influx of power.
Any comments / thoughts?