I managed that map or someone that was very similar.
The key is to get rid of the sorceresses ASAP.
I used a combination of sorceres, blossom mage and 2 treant.
In the end I had 1 troup of treants left for 3 units which was enough to handle the 3, the rest died while combatting the sorceresses and steinlings.
edit: wasnt the same troups, I had 2 cannoneers 1 steinling 1 hellhound 2 sorceress. the map was the same horrible map layout.
I fought with 1 sorceres(pos4) 2 troups blossom mage(pos 1 and 2) and 2 treants(pos 3 and 5)