I doubt using the level1 Thorns as separate armies is a good idea. They are meant to be fodder, just like Gobots (I still chuckle when I write down the name of the Transformer-ripoffs that are now icky worms...)
So, use Royal Thorns or Dryads to summon them, that way you don't have to fear of losing any. Royal Thorns are available on Debir already, and you can upgrade Warriors or Hunters into them with Training.
On my next walkthrough, I plan to do a Mage with an Elven army. There are so many good elven units I never tried out yet. Even more then I can use. I wish the game allowed 7 units in your army...