shamans and ice

I can't get a fire tower close enough to the second Ic e block, up by the world seal in the cradle of the north. I read that shamans can melt ice, but I don't know how. When I put them by the ice they just go back to their tents! Any ideas?

Have you built one of everything and done all of the research? Once done, you should be able to send all of the army to destroy the ice blocks.