Actually, the force field lasts for 2 turns, not 3!
Regarding the complications and unnecessary information, the question was simply "is it possible?" I provided my method! This is one of the possible methods, and I don't claim it's perfect!
Moreover, an Earth Magic expert is a mandatory requirement! You can lower the hero's stats (50 spell power, 50 knowledge - you can even lower them further), it will just take more turns.