The most frustrating moment in any game is when you find yourself dying in the same spot over and over, without making any progress. Even though sections like this compel you to tear your hair out, they are crucial to the gameplay. After all, you feel no satisfaction upon completing a game unless it provided a challenge.
Because bosses are designed to put all the player's skills to the test, end-level enemies have to be distinctly arduous. Although these confrontations won't be easy, you should pull through so long as you are patient, adaptable, quick, and opportunistic.
However, there are certain bosses that aren't just tough - they're cheap. Some enemies are so unfairly brutal, they feel legitimately broken.
Look, we all know gamers love a challenge. But it's not fair if the enemy can kill you in one hit, has a microscopic weak spot, or gives no indication how to beat them. If there's no rhyme or reason to their attacks, how can we strategise? If the boss doesn't telegraph their attacks, how are we expected to emerge triumphant?
Although bosses should put the player through a brutal battle, the developers went way too far with these guys.
12. Cyberdemon - DOOM (2016)
Since his debut, the Cyberdemon has earned a reputation as toughest monster in Doom. After seeing him pop up in every instalment, you'd think we would desensitised to this robotic behemoth.
But while you're navigating the Lazarus Labs in Doom 2016, the Cyberdemon bursts into the room, reminding you why he's the baddest denizen of hell. Because he has a rocket launcher fused into his arm, the standard strategy against the Cyberdemon in previous entries is to strafe around to stop him locking onto you.
Well, that tactic doesn't work here.
Not only can the monstrous cyborg blast you with ten rockets in a second, he can shoot a dozen missiles into the air, which come crashing down on nearly every section of the arena. While you're trying to find a safe spot, the Cyberdemon will launch himself at you, cutting your health to nothing.
Just when it looks like the snarling beast has popped his clog, he transports you to hell before initiating the battle's second phase. Not only are his attacks here faster and more powerful, he summons walls on both sides of you, making it impossible to strafe around to avoid his assault.
Even if you're equipped with the BFG, coming out on top is a miracle.