Bravely Default -
So the next dungeon is the Underflow. This place is hard! Probably the most difficult dungeon for the challenge since the Temple of Wind. The first floor isn't too bad, just introduces some of the enemies, but after that, whoof. Might as well break it down by enemy.
-Red Flans are relatively benign, and each one can be brave-blitzed by my stronger offensive PCs. Their fire magic is pretty good, or they can poison. They alone cause me to pull out the two Flame Charms I have (adding the third when I pick it up in this dungeon), though I keep the Hermes Sandals.
-Flare Lanterns are jerks. Seriously, they ruin everything and cause several resets. Their money move is a MT fire magic which inflicts silence (which prevents sword magic). This completely fucks up brave-blitzes. Also, if four of them ambush me I may just die to the damage. Fights against four of them, or two of them plus two Red Flans, are bad news. If only one appears, it can be killed by a brave-blitz with my Hermes Sandals PC. Oh yeah, and they immune sleep.
-Zombie Minotaurs also immune sleep. They'll use Berserk turn 1 then start doing crazy amounts of damage, and have lots of HP and no elemental weakness. I can spend lots of MP on Beast Slayer to deal with them, and hope they don't stop me, since it takes 2-3 PCs to brave-blitz one and sometimes I fight two at once, or them + other enemies. Or I can toss Phoenix Downs. Guess which I do.
The third floor is the hardest because it features nasty formations involving the above guys. There's more:
-Magicians are actually pretty wussy! They're demons, so weak to the Birch Bow. They have MT Curse which can screw up blitzes somewhat, and MT blind which makes me put Blind Immunity (the Monk passive) to good use. They're usually fought in small formations, though, and have no more HP than Red Flans.
-Demons have a bit more HP, and hit hard with ST physicals, but that's about it. Also demons (obviously), sometimes waste time with Corpse (MT 5-count death sentence, I should always finish the fight before then). Only formations involving 3+ demons/magicians are hard, and I think those are only in the temple of fire itself at the very end. Sleep is an option for both demon-types, but they do seem to resist it some.
-Inferno Golems are total jerks, at least at first. Why? 100% counter to ST physicals, that's why, OH GUESS WHAT I HAVE. Of course, they immune sleep, so my usual strategy for counters is out. Only good news is that their counter is fire, which is good because if I don't resist it, it does a strong 2HKO and outperforms my draining. Speaking of which, drain spellblade brave-blitzes using fire-halving PCs are the way to go here. When I get the Iceflame Shield (nulls fire and ice), I get an even safer option for them.
Oh yeah the final screen of the Underflow itself has a formation with six Red Flans, which is noooope. When I finally get through the dungeon after at least half a dozen resets, fortunately a path opens up for a quick backtrack which is good because by this point I've used up my 99 Potions, and almost all of my Phoenix Downs and Hi-Potions. That brings us to the boss!
Chaugmar (2 resets) - The easiest crystal guardian so far, but still rough. Let's break down his pattern. He starts the battle with perfect defences. For three turns, he'll use one of his regular attacks. On turn 4, he'll transform, dropping his defences, and on turn 5 he'll use Energy Burst, which is a brutal MT physical. On turn 6, he'll make one more of his regular attacks, then on turn 7 he'll transform to restore his defences. Repeat until one side dead.
The first reset is because Energy Burst kills two people despite them being at full HP, so I monkey with my setup. Big thing is to go down to one Ranger, since they're the most fragile (Monks have HP, Spell Fencers have shield/armour proficiencies). I end up going with two Monks, because they have more speed, and I only have one heavy armour anyway. Sword Magic on everyone, Monk skillset on my Spell Fencer.
At this point, let's talk about his skillset. His worst move (for me) is Heart Suck, which drains 2 BP from someone to him. This means he'll brave the next two non-Transform, non-Energy Burst turns he gets, and THAT is bad. He also has a regular physical which tends to do 4HKOish (depends on evade) damage to a defaulting PC, and Soul Suck, which drains MP (obviously not too bad).
When he braves, though, he'll use Blood Suck twice. This hurts. It does magical damage, and when not defaulting it does borderline OHKO damage to most of my team, and thus can 2HKO through default sometimes (not the spell fencer, who activates Anti-Magic and will tank the second). It also heals him for a bunch. FUN FACT: My second reset is because I go for a brave-blitz but forget about all the health he has drained. Whoops.
Anyway, some big realisations I make which help are that (a) because Blood Suck hurts so much, it's often easier just to leave people at low HP. I can always heal the turn before Energy Burst, (b) if people do die before Energy Burst, leaving them dead is okay! Everything else besides Energy Burst isn't THAT bad, and leaving people at lower HP means less health for him to drain.
Besides that I have a choice between using Thundara or Drain spellblades as necessary. A particularly good time to attack is the turn he uses Transform, with Hidden Dragon, either using Drain to heal up or Thundara if that's not needed. Sadly my ranger doesn't have this strategy, so he'll use any spare BP pre-Energy Burst to toss potions. Default through Energy Burst, hope everyone lives, use any remaining BP for more attacks. Repeat. Brave-blitz when I feel I can go over 54k damage done (accounting for draining!) total.
Chaugmar is fast enough to outspeed everyone but the Hermes Sandals wearer (one of my Monks, who needs the Def the least) on occasion, so that has to be accounted for with healing or blitzing (either on turn 7 before transform or for a kill) strategies. I learn this the hard way, but once I do, not too bad.
Overall a tough fight but manageable! I was Level 39.