As a person who usually plays forces over the other classes, you might struggle to kill some of the high res enemies, even on solo mode. It's worth considering a melee setup sometimes. I might be a little biased, though. I'm a huge fan of being a battle mage. As for the unbeatable ep2 bosses... you will NOT defeat gal gryphon on solo play mode. I'm not saying this because gal gryphon will be incredibly tough to beat. But because you will do no damage to it. Hardcore zeroes. I'm not sure what other bosses are unbeatable on solo play mode (ultimate). I found this one out the hard way. I digress, though. In ep 1, you'll do fine with techs. Ep 2 enemies have naturally higher resistance, though. And ep 4... techs still do pretty good damage. You'll notice a huge difference with tech boosts, though! You'll be nuking those rooms in no time, haha!