The Reconstruction

Murdering your way through the prologue doesn't do anything, since you can't level up. If anything it will only weaken you between battles. The boss is difficult no matter what, though you do get a second chance if you fail.

You do get essence in the prologue, but you don't level up automatically, they're spent at in a special menu you only get access to afterwards. So you can't level up during the mission itself.

i actually kept reloading when it became apparant i was gonna get stomped

Nooo, never give up! The show's not over until you see that game over screen! That battle in particular is fast-paced and your healer is almost guaranteed to go down, but the boss isn't terribly sturdy either. You can take him down with only a few casts of Fiery Raid.

Correct me if I'm wrong, but isnt Essence individual for each (surviving) character (as well as half of it for currently recruited ones)? The Prologue Characters are never Part of the active team, I can't see which the point would be either way.

Yeah, the prologue's full of lots of ifs and buts like that. I probably should have kept my explanation simpler, but I have a bad tendency to overcomplicate things. :< I honestly feel the prologue's very poorly designed; I guess Deltree intended it to be a simple no-consequence sandbox where people could get used to the mechanics, but the end result is way too complicated and it goes against the grain of many seasoned RPGer tactics (like the "keep everyone alive to preserve exp" thing) without giving you any reason to suspect you're supposed to take it easy. Just making it so you don't get essence at all, to make it clearer that this is an offshoot thing with no bearing on the main game, would have been a wiser choice. Cutting "Peaceful Approach" might have been a good idea too.

(As with many things, I feel IMTS did this better -- exp isn't split, you don't work with throwaway characters before getting the main cast, and you're exposed to mechanics gradually instead of getting everything dumped on you at once.)

By the way, if you ever get stuck on the other bosses, I've outlined some basic strategies in my running review series. Don't look at them until you've reached that point in the story though, I'm pretty liberal with spoilers: boss 1, boss 2, boss 3, chapter 4's optional boss, boss 4, and a certain chapter 2 quest I would have really appreciated some help on my first time through.