Long time ago I built a deck, being inspired with Incoming army
concept and its discussion.
You can already simulate it by taking all replacing rares in your deck, and using scepter of summoning (actually, there are 16 replacing rares, so you get the added benefit of throwing out one you don't want like Necropolis or something). This doesn't seem to have broken the game, though.
I took all cards from list -
"Summons a rare, no keyword, replacing card"
So the list is actually: Architectural improvement, Atlantis, Danai present, Dark horde, Elven army, General's army, Market week, Mountain of faith, Myr's academy, Necropolis, Plan of salvation and Reunion of the tribes.
- and added some strong stock-increasing cards, plus almost all Restoration.
That was an early version of my beloved Restoration/replacement/jack-of-all-trades deck (stats: 275-166, so you probably played against it and know what I mean). Then it was changed many times, lost Scepter of summoning, almost all stock increasers and half of rare hand replacers (just FYI - remaining replacers are Plan of salvation, Danai present, Necropolis, Reunion of tribes, Atlantis and Mountain of faith). It got so many changes (tokens, Restoration as base, additional defense, Wheat farms removal) that I hardly remember the first version.
But I still remember that Elven army was the very first card I removed from this deck, just because the only useful card from replacement was Princess of elves. Pitiful damage, requires high facilities (5/5/5 and higher) to be really effective resource card etc.
Now, with introdiction of Elven market, Elven apprentice and Elven sorceress, this card can be kinda more effective. Add these three cards in list, and remove Elven fighter, Elven archer and Elven marksman. With Elven priestesses, Elven ranger, Elven enchantress, Princess of elves and Elven warlock this would become a nice resource-gaining hand without any pretensions to be aggressive and tries to cosplay General's army.
Of course, it should be also renamed into Elven forest or something like that.