Demonic Spiders: Turrets. Four punchy bullets, high damage sponge, and if you thought that was bad, there's an arena match that has dozens of them everywhere and you have to survive.
Game-Breaker: Has several things that could qualify:
The Berserk/Throwing combo. With both, you can unleash a very fast and non-stop flurry of axes.
Dr. Deflector. You can use it to bounce off enemy bullets, and they do the same damage, which can kill even Artifact Jacks quickly.
The "GOODBYE" cheat code, which is supposed to make the player suicide. It actually does like thousands of damage in a way that would instantly fill up your Stoneskin talent if you have it.
Any amulet with the "Guardian" effect. "Become invincible briefly when hit." doesn't fully explain what it does. It actually gives the same invincibility effect as the Restore spell. Which includes removing any status effect you currently have. In short, the amulet will make you effectively immune to every status effect in the game. They can also show up at literally any point in the game, so it's possible to have one within a few minutes with some luck.
Scrappy Weapon: Not just weapons, but also artifacts and spells as well.
The Shock Orb spell is pretty mediocre at best, as it's just a slow bullet that zaps other enemies, and it only does it once per second. When taking in mind other bullet spells like Toasties or even Cryozoid, it falls way behind in terms of damage potential.
The Brambles spell is virtually worthless, as all the spell does is an area-of-effect Damage Over Time that only does 1 point of damage note If you're playing with the Easy modifier, only 2 points of damage per second. The catch? Even if you put more skill points in this, the only effect you're gaining for this spell is extra range and duration of the brambles. Not even damage. The lack of damage improvement for this spell makes it virtually unusable for late-game enemies as they have more health into the hundreds.
The Question Axe is pretty awful for its concept, as it only gives you 10% discount on shops. The catch is that you actually have to equip the Question Axe, and most of the time in the endgame, shops barely have anything to even help you as their stock is incredibly outdated compared to the vast amount of Artifacts you would end up having by the time you start building Crystals on Madcap Mode.
The Imaginary Parka is considered to the be the worst artifact that you can get in the game. Not only does it have no stats whatsoever, but it's special effect is basically giving you a random second immortality. The problem is that this special effect is completely random, and the fact that the parka has no stats gives it no real reason to even equip the parka over the other parkas.
That One Attack: Army of One's spread rockets, He can combo you with his rocket burst gun, which can drain a lot of HP if multiple rockets hit you.
That One Boss: Gourdzilla, since it has a massive legion of Yellow Roses that frequently get in your way while trying to reach it, even when you're in range to attack it.
Killbor, despite not having any special abilities, can hurt you for a lot of damage. In addition, he has a lot of health and can frequently spawn Nuclear Bokboks that explode on impact.
That One Level: Really Never Get Shot, there are turrets everywhere and there is almost no spot where you can avoid getting hit by the rockets. Have fun trying to survive or destroying the turrets! Don't forget that the description says "Save your money" as each match requires you to pay first and then enter. This arena match is incredibly hard if you're doing it without a Dr. Deflector, which allows you to tank and reflect the bullets.
