Boss battles that just involve knowing when to attack, when to heal, and when you're lucky aren't taxing. There's little strategy involved, and when you're facing an opponent who hits hard enough to take 1/3 of your HP at a go you're not likely to benefit from sapping its defence or trying to lull it to sleep. However, boss battles such as this are an exciting back and forth.
Such was the case with the Dreadmaster. This is the boss that stood between me and another fygg. It's also another boss that beat me before I beat it.
Being three levels under the recommended 32 (over at Dragon Quest Wiki), I think luck was mostly on my side. Mostly because Nizk and Thoth kept getting access to their individual coup de grace techniques.
Unfortunately, Peridot or Kleftis never saw a single coup become accessible. Peridot's would've helped speed up the healing process, but Kleftis was simply a tank in this fight. With 180+ HP, and a physical attack that consistently dealt about 30 damage (while the spell Boom did twice that), she's clearly the definition of a tank.
Along with this triumph, I can say that so far nothing weird has happened in-game. Collecting the fyggs in my own order doesn't seem to have derailed anything just yet.