I've made it through a few dungeons now in Final Fantasy Legend III and came up against a boss named Chaos. His first action was to use an area damage spell which hit my party for anywhere from 40-75% of their max health. Then he did it again, which killed my cyborg outright. I tried the fight a few more times and while he didn't always start with double quake he would use it from time to time which was a real problem. When he didn't use quake he'd attack for more damage than my heal could take care of. I have two people with heal spells so I could theoretically win if he only used his normal attack and didn't chain them into my cyborg. But I'd have to go about 20 rounds with nothing going wrong in order to win and that just feels really unlikely.
My cyborg has an infinite use healing spell which is pretty great for fighting in a dungeon. (I can spam it out of combat to heal everyone to full.) But he can't do any damage, his heal is for half a normal heal, and he has half the health of my other characters. I think in order to beat this boss I'm going to need to level up, change him to something useful, and maybe even go searching for a town and buy some better gear.