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.
The Flash RPGs:
Big Lipped Alligator Moment: The Rockstar enemy in Zone 3 of the first game. What the hell is a rocker doing in a shamanic community?!? And he has the boss music, no less!
Demonic Spiders: This happens a few times, but Gregor the cockroach stands as the most prominent (aka most annoying) example.
The Blood Hounds in Hew are extremely painful and pretty tough.
Game Breaker: Biological class happens to have one when the player combines Predator Form, Toxicant Form, Shadow Blend, Crystallize, Agile Exposure, and most importantly, Withdrawal. Almost always kills the victim in one shot of Withdrawal.
An Electric Psychological can be very powerful. The bread and butter spell of the build, Shock Therapy, not only deals heavy damage but also debuffs enemies, and Electric Storm restores the Focus you waste on Shocking right back. There's also a skill providing a substantial passive increase for Electric damage, and Wraith Form gives so much speed that almost every spell crits for massive damage. In addition, weapons providing massive boosts to electric damage are everywhere, as opposed to weapons with boosts to dark damage, which are very few and far between (and none at all in the endgame). The Achilles' Heel of a Psychological is the health, but the Force of Will shield and the aforementioned Wraith Form speed boost take care of that - most enemy attacks miss and those that hit get absorbed. Putting enough points into the dark spec to achieve Psychopath form results in incredible pain for the enemies if you assume both forms at once.
Goddamned Bats: potentially almost any enemy on higher difficulty levels. The monsters have just as many tricky spells as you do, and even a pair of lowly prison guards can keep one of your characters stun-locked for the entire battle. And that's not getting into all the healing and ablative shields being thrown around...
Nightmare Fuel: Some of the skill descriptions for a Shadow Psychological can be this.
That One Boss: Baron Brixius, in both games. In Sonny 1, only your Guest Star Party Member can do enough damage to get the Baron's HP down to 0 in anywhere under 100 turns, which means that Sonny and Veradux are pretty much stuck with the jobs of keeping him healthy and helping him do even more damage. Then you get Player Punched when said Guest Star Party Member becomes the Final Bossin the very next fight (thankfully he's not hitting for thousands upon thousands of damage anymore). The Baron is even worse in Sonny 2. First of all, you don't get a Guest Star Party Member to help you. Furthermore, the Baron has some very annoying new tricks. First and foremost among these is Tick Tock, a debuff which lasts for 10 turns, takes away 10% of the victim's life every turn, and reduces all healing done to them by 50%.And it can't be dispelled. And just to make this worse, Baron Brixius loves to use it as much as he can... which is about every 6 turns. And he has just as much health as he did the last time (48,269... and that's in the easy mode.) Your only hope is to whittle down Baron Brixius's Focus to near nothing in order to force him to use Deep Burning, a move which fully restores his Focus at the cost of about 10% of his life. And once he can no longer use Deep Burning, he starts wasting his turns with actions which do nothing but weaken him. Good luck pushing him to that point, though - unless you've maxed out Disrupt (a move that you can only get with the Biological class,) you'll need it.note Oh, and just to insult you, Baron Brixius is an imitation of Tim Curry, and the epitome of Ambiguously Gay. Who the hell is his voice actor?!?!?