These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Whaler's defense will weaken as he gets new heads. After getting two heads, he can be killed with a single Ritual. He also has a huge weakness to silver.
Many of the Brothers can be either this or That One Boss depending on which glyphs you have. For example, Pit is probably the most difficult boss in the game without the Repulse glyph, since it's nigh impossible to dodge his missiles...but if you do, you're pretty much invincible throughout the whole fight.
Triumphator is a Stationary Boss with pitiful range. Though he isn't affected by most attack glyphs, you can just keep on lobbing Color at him until he dies.
However, this could be a Subverted Trope; just because a boss is easy to defeat doesn't mean they can't mess you up indirectly. Painting Color on enemies is very inefficient compared to using attack glyphs, and since this game has such a heavy resource management aspect, even if you defeat a boss easily that way, you can end up wasting a lot of precious Color.
Crowning Music of Awesome: The music is generally very atmospheric — eeire, haunting, and lonely, but at times peaceful and melodious as well, which is very fitting for the Void. You can download the whole soundtrack (and some concept art) on the official site. Notable examples:
The music for the Void overworld itself is fitting for the overall feel — quiet, but also somewhat eerie. In addition, every chapter features a remix of the same tune to fit the mood even better. Of particular note is the final track, which combines elements from all the others, as well as the title theme.
All of the battle music, particularly the one for the flache — it's ominous and the tune sounds very much like something a Knight Templar would play.
The music for the Adit and the Nameless Sister's sanctum after her death are suitably epic for the Wham Episodes that occur there.
Demonic Spiders: One of the enemies is a creepy, flapping, screaming black thing that disguises itself as a sprig of Color and bursts from the ground to attack you if you try to take it. They are difficult to predict and nigh-impossible to kill without taking damage at least once. Fortunately, you only encounter them if a realm is sufficiently damaged to warrant their appearance.
Hell Is That Noise: The walking sound of the venus flytrap-like creatures, as well as every single sound emitted by the crow-like creatures. See Nightmare Fuel below for details.
Some of the Brothers - Tyrant, Patriarch, Warden and Mantid in particular. Some of the Predators also qualify as this.
But they're Nightmare Retardant compared to the Scorpio. Dear gods, the Scorpio. It's a being (or conglomeration of beings?) that appears when you've dealt significant damage to a realm. It/they destroy your trees, preventing you from planting any more Color — something that no other creature can do. And all the while, you're aware of the knowledge that this is your fault. But worst of all are the creatures that come with it (that may well just be another part of the Hive Mind) — hideous, venus flytrap-like black plants that hold Color drops in their centers. If you try to take the bait, they attack you (they'll also kill any fireflies that are tempted by the Color in seconds). Oh, and you can hear their footsteps no matter where you are (it's not muted with distance). However, their attempts at luring you with their Color are almost laughable, since it's such an obvious trap. That's where the other creature comes in. It uses sprigs of Color as its trap, and there is no way to tell if a sprig is real or not. If you do uproot the creature, you'll be greeted by a hideous, crow-like thing that emits a soul-piercing screech that is garaunteed to turn your blood to ice. They're pretty hard to kill, too. There's also no explanation for what the Scorpio even is. It's not a Predator, since it doesn't devour Color, it just kills it (it even uses it as bait instead of eating it, which is simply bizarre by the story's logic). Is it an alien being from another dimension, which is why it can only appear when significant damage is dealt to a realm? Is it formed from parts of the ruined Void itself? Is it the antithesis of Color? Who knows?
When you fight him, Warden can trap you in his cage. The results are... unpleasant.
Squick: Yani takes the form of young ballerina esque girl hiding anxiously in a pillow fort in a shattered-looking squalor of a house, walls splattered with blood and covered with empty beer bottles. The place almost reeks of child abuse. You can see her naked!
Challenging Patriarch to a duel to the death results in him sounding incredibly heartbroken and disappointed, and subtly implying he will only put up a token fight, allowing you to kill him so you can learn how to fight.
Tyrant isn't lying about being the strongest of the Brothers. His poison gas saps your health extremely quickly, and he's quite fast, making it difficult to hit him with attack glyphs. His vulnerability wheels also fall off sooner, so you'd better have a ton of his primary vulnerability Color if you want to win. Fortunately, it's difficult to anger him, since he's in charge of two Sisters, not one.
The Pangolin is a trick boss. The game implies you can't bash him to death with color from the safe zone, but it is actually quite possible, and much safer than using the Web Glyph like it suggests. This is going to damage Uta's realm quite a bit, however.
Unfortunate Implications: Many say that the game is a statement against sexism and patriarchy, emphasizing all the negative traits of men in the Brothers, and depicting them as the villains. However, it can just as easily be said that the game simply uses patriarchy without really criticizing it. The fact that the player gets to constantly see naked, vulnerable, and powerless women who constantly give out Fanservice does not really help this image.