If bosses keep attacking you with critical hits and you keep dying, there's a simple way to avoid it. First, you need access to the paladin vocation, and you need someone with 100 skill points in shield. Get you paladin to level 40 or maybe a little lower, and put all skill points into virtue. Eventually, he will unlock Forbearance, which protects all members of your party at once. Then, go Swinedimples Academy, talk to the shield trainer. Go through the two quests for the shield, and when you complete the second one, (100 shield points required to start the second quest) he will give you secrets of the shield scroll, which lets you always block critical hits. Combine this with a character with forbearance and really good armor, and critical hits killing your party are a thing of the past. So you have one character to tank and take all damage, a priest to heal him when his health gets low, a mage to oomph your second damage dealer and to deal magic damge with kafrizz/kafrizzle. It might take a little longer to kill them, and it'll take a while to unlock both these things, but they are totally worth it for legacy bosses like baramos and for the final boss corvus.