Even Evil Makes Mistakes

"Failed? Doctor Doom does not fail!"

- Doctor Doom

Even Evil Makes Mistakes is a scenario about a villain whom, during performing something evil, made a terrible mistake that resulting disadvantages on their side or worse, defeat by the hero.

Overview
Over the course of conflict between good and evil where the hero finally defeated a villain, the said victory is not always contributed by the hero alone. When the wrongdoer worked on his/her evil schemes, he/she sometimes missed some flaws in the said schemes, resulting a loophole which either resulting the said plan not goes like what intended to be or gave the hero better advantage.

Aside flaws on evil plans, other forms of mistakes that a villain done that causes severe disadvantages in the conflict between good and evil are:
 * Trusting a particular minion too much: The villain may had a minion that they trusted like family, but he/she failed to see the said union's treachery, whether due to the said minion being a spy from the hero's side or a power hungry character that worse than the villain him/herself.
 * Overestimate Goodness: Some villains may done horrible things or evil so much that they sees various forms of goodness (ex. love, friendship, etc.) as useless red tape that should not taken seriously, which turned out to be their downfall as the hero managed to triumph over him/her due to strengthened by support from the said hero's loved ones and friends. Not only that, the villain may also not taking any serious precautions to dealing minions whom turned against him/her due to either their loved ones being threatened or clashing view about goodness. Had the said villain not comprehend how goodness can keep the heroes forward, the downfall won't surprisingly disastrous.
 * Enjoying The Hero's Suffering Too Much: The more sadistic villains may sees the hero's suffering as fun, even so far to ruin his/her innocence for greater pleasure, but the said pleasure resulting them lower their guards, unaware that torments that they done instead made the hero become more dangerous, particulary if the said torment strengthened whatever resolve that they had. Im other case, the hero allowed themselves to be tortured so the villain would be too distracted from handling anything else.
 * Armed a captured hostage: Some villains who held a hostage may later proved either too arrogant or simply an idiot who doesn't know how to ensure their said hostage from becoming a threat as bad as heroes who tried to rescue him/her. These villains may either experimented on the said hostage by gave him/her powers against his/her consent, locked him/her near their weapons/gadgets cache, or put an armed weapon near him/her that will active and killed them if they wished to. But if the said hostage unexpectedly turned their given powers/weapons/gadgets against these villains while the hero still looking for him/her or occupied in the fight against them, this proved to be their undoing. This form of mistake would be embarrassing had most of the credit for defeating these villains given to their hostages.

Examples

 * Discord: Made the mistake of making a deal with Tirek and as a result was betrayed by him.
 * Jasper: In her pursuit to get her revenge on Steven and the Crystal Gems, she made a mistake by fusing with the Snow Monster and turned herself into a Corrupted Gem.
 * Dr. Heinz Doofenshmirtz: He overestimated his 2nd dimension counterpart's evil nature that the latter decided to disposed him after they got Perry the Platypus and device for travel between dimensions fixed.
 * Bebop & Rocksteady: They intend to mutate themselves into a 2-headed mutant turtle, but Leo tricked them into adding the Shredder Elite to the mix. The two evil mutants fall for it with a big consequence, with the three of them being fused into a Mega Shredder.
 * Janja: After he kicks out Cheezi and Chungu from his clan, he took in their place Nne and Tano - two new hyenas, which are smart as him. During the plan, which involves diverting The Lion Guard's attention, while they hunt for gemsboks, Nne and Tano treacherously pushed Janja to the cliff.
 * Aldrich Killian: He has dangerously used Extremis serum on Pepper Potts to demoralize Tony Stark/Iron Man as he beat the hero. Unfortunately, in the middle of his boast over his seemingly triumph against Tony, Pepper (whose body revealed to be compatible with the serum) suddenly showed up and smacks Killian before defeating him by herself, resulting his humiliating defeat.
 * Bellatrix Lestrange: Her pleasure from torturing Hermione made her lower her guard, allowing the girl to take a sample of her hair that was required for a later plan to infiltrate Gringgots bank where one of Horcruxes was kept.
 * Mojo Jojo: When Professor Utonium revealed that Mojo, then a destructive lab monkey simply named Jojo, was the reason he knocked Chemical X into the concoction that created the Powerpuff Girls, Mojo was stunned that he created his own enemies. When this is observed in an episode of Villainous, Black Hat and (especially) Dr. Flug were outraged with this.
 * Cyclonus: As he repeatedly punches Ultra Bee as Galvatronus, Cyclonus states his allegiance to the Decepticon Empire and his failing desires to restart it by summoning Megatron. However, Cyberwarp, who has been trying to object these actions from the beginning and having enough of all the suffering the Decepticon High Council is inflicting on the galaxy, suddenly turns on him, giving Ultra Bee an opening to finish him off.
 * Joseph Korso: Realizes that he didn't betray Cale and Akima because he was working for the Drej. But it turns out that Preed was the traitor who did worked for the Drej.
 * Kent Mansley: Realizes that he made a foolish mistake after snatching the walkie talkie from General Rogard to launch the missile as General Rogard angrily informs him that they will die for their country when the missile re-enters the Earth.
 * Megatron/Galvatron: Galvatron made three mistakes in the end of Armada:
 * Ignored the threat of Unicron till Starscream sacrificed himself, which made him fear the end of the war between the Autobots and the Decepticons.
 * Challenged Optimus Prime to a duel to death which reawakened Unicron when believing the threat of the latter to be over.
 * Released himself from Optimus' grasp with a retractable knife to plunge into Unicron's maw seemingly to his death.

Quotes
"(Rogard angrily berates Kent for doing a dumb thing.) (General Rogard: That missile is targeted to the giant's current position! WHERE'S THE GIANT MANSLEY?!) What? (Kent looks at the Giant who is glaring at him and thinks of something.) Oh, we can duck and cover. There's a fallout shelter right there. (Rogard cuts him off.) (General Rogard, angrily: THERE'S NO WAY TO SURVIVE THIS YOU IDIOT!) (Kent becomes nervous.) You mean, we're all going... (General Rogard: To die Mansley, for our country.)"

- Kent Mansley realizes that he made a foolish mistake as General Rogard angrily informs Kent that they will die for their country when the missile re-enters the Earth.

Gallery
NOTE: The limit is for 20 pictures only