Sounds like it has potential, a few important notes.
I very much think killing a hero should award some elixir rather then just winning, and primarily without the use of your heroes orders you are at a big disadvantage as apposed to simply loosing.
The systems in place seem good however I think the amount of elixir required to win should be raised significantly perhaps doubled or tripled from seven that way the game is more about actually fighting each other and less about some silly scavenger hunt where you avoid fighting. This allows elixir to be a powerful advantageous resource used for giving your heroes abilities or with careful management a way to win. This way it will encourage strategic play without actually discouraging what this game is all about WAR.
I have seen strategic resource systems work very well in a very similar game PoxNora, as well as a fun rts the Dawn of War series. In both their were objectives and key areas you could get to give you these extra resources, neither of them were actually used to just directly win the game just simply to give you the edge. Honestly I don't even like the idea of these resources strait up winning at all, they really should just be resources, but if you really want that alternate win in there at least make sure you have it high enough that you do not discourage fighting your opponent.
And on a side note I really like long and hard battles, it feels more like a war then just a skirmish, and I like large armies. Most competitive players in this genre would agree that smaller shorter modes are more for casual play. The competitive mode where you should focus the balance of this game should be in the higher ap bracket like the current 800 area and should have more like 20 or more turns to win. 10 turns can force people to play just an all out fight rather then strategic maneuvering and careful planing. While a turn limit needs to be there it should only be there to prevent stalemates as apposed to put a rush on the game.
Lastly while I personally like the new direction (at least if my ideas for it were used
) more then my beloved deathmatch. The simple fact is the majority of people still prefer deathmatch and it is both what attracts and keeps new players. Every new map feature you add, adds more to the already steep learning curve. Truly learning how to kill your opponent in a variety of different ways is already enough to take in, and adding more content and balance adds just as much depth and strategy to the game. The main point of this is if you choose a resource system or any extra objectives be sure to make it simple and don't let it detract from the best aspect of the game.