First off I would like to say I love discussing game ideas. So on to it!
Lets break down what your new building does...
Deletes the following buildings:
Okay, So now lets look at all the functions compiled from two buildings now do into one.
Increases Resource Cap (I am assuming because that's what Sylvan Shrine does)
Builds Forest Spirits (Provides Wood)
Builds Deer (Provides food)
Builds Unicorns (No gold income now, provides food by eating unicorns (elves way?)
Now has a stone trickle
Increase resource income while Female Warden is present
I can make one building to do all functions. In fact, I would make about 14 of these buildings to make an insane income and high resource cap.
One building to upgrade reduces total crown costs to city.
Now that I do not have to have miners I can focus my population cap on city defense units.
I go to hell for eating unicorns. This is an elvish sin.
Now, what will we have to do to the other two races so they are equally balanced to our new elves faction building? Have you played them yet? I am sure they will complain because elves will now only have to build one building for resources but also they will not have to spend as many crowns in research. Also, they will complain a bunch because they will have to use half their population cap on miners while we will have a full army defending our cities.
But other than that I play Evles and I am all for it.
PS: As is it would be way too over powered. What changes could we make to your idea to put it more in line with the other factions? I am always open to discussion.