New chapter! The game takes a notable jump in difficulty starting on Floor 13, sort of like the jump between stages 3 and 4 in any Touhou game.
Let's Play Labyrinth of Touhou - Chapter 16
This is so unfair! Why do I have to do this with you?!
Reimu and the others were getting fed up with our constant bickering, so they forced us to spend some time together to patch things up. Either that or they were hoping we'd off each other. I suppose they think they have enough to worry about with Rinnosuke going rogue and Yukari still on the loose. Trust me, this situation pleases me no more than it does you.
Well, it's not my fault! I never did anything to you!
But you did freeze all my cute little frog underlings! What did you think the goddess of frogs was going to think about that?
Heh, I always try to thaw them out afterwards. No harm done, right?
If by "thaw" you mean "shatter", then yeah, sure. How would you like to feel what that's like? I'm sure that'd be easy to do with your wings.
Hey hey hey! Hands off the wings! Can we just start the next segment already?
Fine, but you're not off the hook yet.
The 13th floor is the most puzzling floor yet. Upon our arrival, we came upon a moss-covered ruin of circular pillars and stones surrounding a single small open area. Rather than the maze of teleportation sigils from Floor 7, there was but one single teleporter standing in the center of the ruin. It did not seem to be functional yet, but scattered around the ruin circle were seven mysterious black crystals, each marked with a number from 1 through 7. This was obviously another sort of puzzle.
Only 7? Then this should be an easy puzzle! I'd be more worried if there were, like, 2 more!
How like you to think that it'd be so simple. Where's Patchouli and Alice? They're usually good at this sort of thing.
Um...Reimu says they want us to solve this. Something about "learning teamwork" or some other nonsense.
Wait, I have to figure this out with only an idiot like you to assist me? Reimu! Reimu! Please, anything but this!
She's ignoring you...
What kind of shrine maiden would ignore the demands of a goddess?!
Don't worry! The Strongest is also the Smartest! I'll solve this single-handedly!
We're doomed aren't we?
Here, I'll just fiddle with a few of these black crystals. That'll do something once we step on the teleporter, right?
Did you even remember which crystals you turned on?
Who cares, let's just go!
See? I told you I'd get us somewhere!
Yeah, but you don't even know where we are now!
The Strongest doesn't have to worry about getting lost!
Ugh, whatever...this place seems to be a catacomb of some sort. Perhaps it's tied to the ruin.
We can follow this passageway! Come on!
Wait, hold on. What's this?
It appears to be some sort of message carved into the ruins. #1 and #5? Would those be referring to the black crystals back at the ruin circle?
Hey, I found a way out! Come on!
Calm down already! Some people here are trying to actually solve this puzzle here, you know.
Just a little more this way, and...whoa!
Looks like we're not welcome here!
Well, we've never been welcome on any floor, truthfully speaking.
But these guys are so fast! Whole groups of enemies here can attack us before most of our party can even get a turn.
Then I guess we'd better put you in front, right?
Whatever. I just want to get through this ordeal in one piece. Whether or not you remain intact is more or less trivial to me. Now, where's the exit...
Hmm...a one-way teleporter that returns us to the main ruin circle? Perhaps different combinations of active crystals will take us to different parts of the catacombs. If that's the case, then it looks like it'll take a while for us to figure out the right combination. If only there were more clues...
Leave it to me! I can play with the crystals again.
So long as you're willing to be the scapegoat if things go wrong...
See? I told you I knew what I was doing!
I suppose even a broken watch is correct twice a day.
What's a watch?
Ignoring your stupidity for a moment, I'd guess that the black crystals each have a different value, and we must find a way to create a combined value of 77 before we can move up to the next floor.
Ha, I could have guessed that!
If you're so smart, then why don't you think of a pattern for the black crystals' values?
Oooh, maybe they're each a multiple of 9?
You dimwit, that can't add up to 77!
Huh? It doesn't? Then maybe they go something like 9, 19, 29, 39, and so forth?
That...actually sounds feasible. It's strange having to admit that to you.
Hooray! See, I'm smart! So we'd have to hit switches 1, 3, and 4?
You can do basic arithmetic too? That makes even this goddess ask: will wonders never cease?
Why am I not surprised that your answer was incorrect?
Hey, at least I got us somewhere new, didn't I?
I guess it's not too unexpected. With your suggestion, hitting switches 2 and 3 would be akin to hitting 1 and 4. I'd venture to guess that the correct code has no overlapping combinations.
Well, if you're so smart, then you figure it out!
Gladly. Let's see...logically speaking, this is a code that has no overlapping combinations, yet can still hit every single potential number...
Boring! While you're busy with that, I'm gonna keep looking around!
Ha ha! Look, wonderful treasure! I just keep succeeding at everything!
Except finding the correct path to the next floor, apparently.
Well then, what have you accomplished, Miss I-Think-I'm-So-Smart?
Hmm...something related to binary, perhaps? That could work.
I fear for the brain cells I'd lose trying to explain that to you. But this might work. If we know that at least crystals 1, 3, and 7 need to be turned on for us to proceed, then the only remaining crystal we need to turn on is...
Of course! That's it! All you have to do is activate-
I got it!
What?! How did you know the correct combination was crystals 1, 3, 4, and 7?
Because 7 times 4 minus 1 divided by 3 equals 9!
That...makes absolutely no sense. You have no idea what you just did, do you?
I have to admit: looking back, these extensive ruins are actually kind of pretty.
But I don't ever want to see this place again.
Hmm, we agreed on something? Maybe we aren't as completely incompatible as I had thought.
So you'll let me freeze frogs again?
Nevermind. Just the sound of your voice still makes me want to kill you. We'll settle this back at the mansion!
Bring it on! The Strongest never backs down!
~ Suwako Moriya
And some spoileriffic gameplay notes, including the explanation for the floor's puzzle and all the combinations to use:
The 7 crystals on the floor each have a value equal to 2^(n-1), where n is the crystal number. So in order, their values are 1, 2, 4, 8, 16, 32, and 64. There are some 19 different areas on the floor that you can reach using particular combinations of values. Many of these areas (especially the ones with multiple valid number totals) just contain hints for the correct combo to reach the next floor. Some hold valuable items, though. Here's where all the treasure lies:
0-10 : Green Dream
11 : Cosmic Muscle/Energy Crystal/Shuten Douji Bracelet/Omoikane's Insight
30 : Glaive of Pain
59 : Holy Win
64 : Robe of Twilight
78-87 : 10,000 Skill Points
88-97 : Magic Rainbow Crystal
98-100 : 15,000 Skill Points
101 : Ribbon
108-117 : Star World Ring
118-120, 122-127 : Event icon, if you're doing the Flandre sidequest
121 : Lion King's Soul
(Info taken from the game's wiki)
The big prize here is the Ribbon, which, as any Final Fantasy fan will tell you, grants you awesome protection from all status ailments. This lets Remilia or Tenshi use their really good self-buff moves without accidentally poisoning, silencing, or paralyzing themselves. You definitely want to get it, as it's the only one you'll ever get unless you get really lucky with a single powerful enemy's abysmally low drop rate on Floor 20.
As for the enemies on the floor, the main ones to watch for are the Spiral Diver, Rail Insect, and Amazoness Rabbit. All three of them are very fast and will likely outspeed most of your party, plus are capable of usually taking at least 1 multi-target spell unless you're totally overleveled. Spiral Divers have an absurd 180 speed; only Chen and Aya are likely to ever surpass them at a reasonable level here, and even then they'll probably need some speed-boosting equipment. Unfortunately, they resist Wind, so Aya can't 1-shot them, and Chen might need to use her attack boosting spell before she can either. They also hit very hard, and I think one of their attacks has some sort of defense-piercing property, so Tenshi might not be able to survive 2 at once. Komachi and Meiling can usually take it, although prepare to lose lots of TP over it.
Rail Insects and Amazoness Rabbits have 152 and 150 speed, respectively, so a few select characters like Remilia, Sakuya, and Marisa can outrun them with a bit of help. The Rabbits use strong single-target attacks, while the Insects specialize in status effects like Poison and Paralysis. In general, you'll find that starting on this floor most enemies may require several spells before being defeated, so prepare to start spending more SP than you're used to in each battle.