Ive been thinking about how, among all the ideas, there are two basic ways to spend mana. (talking about mana specifically, not essence)
First there is in-battle mana, which either can regenerate in-between battles.
Secondly there is mana used for everything else under the rainbow, outside of battle, which lowers your battle-mana for the duration of that turn...
basically they are the same mana, but the more mana you invest into the world map, the less you have available in battles.
the key difference is that investing mana in the worldmap, as opposed to essence, is a temporary loss to battle mana, for the rest of the turn. while essence is gone forever.
One possible alternative is to have essence to be used for everything outside of battle, and for mana to be everything inside of battle. However, I would like for essence spending to only be significantly important creations. Therefore, I would like for mana to be able to be spent outside of the battlefield.
Each turn your mana is completely regenerated. This mana when outside of the battle is "mana points" which has no aesthetic difference. However, mana you use outside of battle, for various things, spend your mana points (which is determined by your essence). In battle, your max-mana is manapoints - spent manapoints.
A simple diagram would be that each turn you get X mana. if you spend Y mana outside of battle, every battle during that turn you can use X-Y mana. This is the system I prefer, as its simpler, and each battle refills your mana up to the X-Y mark. However if you wanted no mana recharge between battles, or partial mana recharge between battles, the maximum possible is X-Y.
Lets say you have 200 mana at the start of each turn, due to your essence. Every battle during that turn you would have 200 mana to spend, however you wanted. However, if you used mana to create some special units, or bless the crops, or do a global ritual, or something, then u have lets say 150 mana left for the turn. Then during battles you could only use 150 mana. This assumes a complete regeneration of battle mana after the completion of a battle. While perhaps not the current trend of thought, I think it would be better able to separate mana used inside of battle and mana used outside of battle ... and make mana used outside of battle more significant.
and in this way actual essence used would be far, far more significant than any mana-burning spell.