Impossible, Mage - No unit loss.

[Metathron]

I did go to the mines with the intention of activating Lina and hoping to get cannoneers. Luckily, they were available in the first areas, so then I also opted for giants (there were 4 available). While they are lacking in the damage dealing department -- which I guess is true of all level 5s -- they are excellent as a meat shield, i.e. blocking some choke points.