What are some of the most frustrating bosses (or gaming moments) that you have encountered and how did you overcome them?

For me, my most recent frustration comes from Divinity 2: Raze's Fortress. (most of the frustration is because the game is very VERY good and quite balanced... most of the time :p )

He has 2 healing chambers and, from what I can tell, an infinite number of adds that spawn. You have to pull tiny levers to keep him from healing in the chambers, but the chambers reset, so you have to time your damage, your position, and the pulling of levers.

Problems:

1. They start you out with your weapons put away, leading you to a few cheap shots from the boss.
2. The mobs tend to swarm around the levers making them very difficult to pull while getting beaten on by multiple mobs + boss. (both from a spacing issue and a targeting issue)
3. Its very hard to target the boss with so many mobs.
4. When I was doing well, I would get stopped by an invisible wall that would not allow me to jump, strafe, roll, or make any FORWARD movement to get to a lever... allowing the boss to heal when I should have been able to beat him to the lever.


How did I beat it? It took about 12 tries. I basically toss it up to blind luck. (wouldn't have been too bad if it weren't for the invisible walls). Normally, this would have been an uninstall after about the 5th try, but the rest of the game is so good, I had to allow a little game-rage to be able to continue ;)

Borderlands - Crawmerax. Especially in single player, where dying means you have to wait for the elevator to descend then ascend again.

I did not overcome it ;__; I wanted to, but the time between dying and getting back into the action just made things far too frustrating.

In some random Diablo 2 mod i played years and years ago, there was some mini boss i grinded for like 5h straight. it was pretty damned frustrating.

I did finally triumph - alas my loot of around 100 gold and neglible amount of exp was not what i had hoped for the feat. I did delete the mod (and D2) not soon after.

Squere Enix's Superbosses, most infamous are Emerald Weapon and Ruby Weapon in Final Fantasy 7 and Yiazmat and Ultima and Zodiark and Omega Mark XII in Final Fantasy XII

TR AOD
There is a boss you have to hit only after grabbing a certain tome of several displayed on pedestals. You can only stand up and move when the boss is stunned which is next to impossible to tell when he's stunned because he looks almost identical to when he isn't stunned. It's not like PunchOut where they went cross eyed to let you know they were momentarily incapacitated.

That asshole Artorias in Dark souls was a bit frustrating, fighting fats&smalls was a lot easier than fighting him.
Moose on the hardest difficulty in XIII was quite a pain.

I played D2 mostly coop, which ramps up the difficulty from single player. We could be running along at a pretty good pace and then enter a new room. There were times where we would die before the room illumination transition effect would finish. (which is pretty much faster than instant as we never even saw what killed us). So we had to run back and try to sneakily pull mobs out of the room a few at a time just to make our way in to see how many named mobs were gathered in the corner by the door ;) This was a modless D2. We learned essentially that we needed to open a door and run and wait a bit before entering rooms... especially if there was a glow around the room. We played up through "Hell" difficulty so this much more prominent later in the game.

Internet.
It was all fine and dandy till I reached 4chand and found /b/.

Melissan or whatever the bitch was called, from Baldur's Gate II Throne of Bhaal.
Never have I been so close to ragequiting a game so near the end.

There was also one Megaman Battle Network game that had a REALLY hard boss, even though the rest of the game was pretty easy. I forgot the number though. I'm guessing it was 5.

Mogenar from Metroid Prime 3. You have to completely drain 4 energy nodes on his body; 3 on his front and 1 on his back. On the hardest difficulty, this can be VERY difficult because the only way to really do this is to use hypermode, but that drains health and you can only attack at certain times.

EDIT: After 4 years, I still haven't beaten him.

The final boss in Giana Sisters: Twisted Dreams.
This was the first time in more than 20 years that I've decided to quit a game...

Basically any and all final bosses, especially Ubisoft bosses (Rayman 2, Beyond Good and Evil, Cold Fear) because Ubi doesn't like to let you save whenever you want to.

In fact, f##k video game bosses in general. When was this boss? Back in '04, I could never get past the bug boss because the keyboard layout was f##ked, and I didn't know that I had to hit a certain key to target certain body parts...

The first boss (some douche with fire hands) on TR3 I couldn't get past, so I had to cheat.

The final form of the last boss in Mega Man Zero 4. He has this "wham, you're dead" attack, and I never figured out how to dodge it. Partially because if you have lives left when you die, you have to fight his earlier forms again, and if you don't have lives left when you die, you have to play through the last stage again, which includes the classic "fight all the bosses" thing Mega Man games have. So every attempt to learn how to dodge it took from 3 to over 20 minutes. I got fed up at some point.

The Kikimore Queen fight in the first Witcher game is super-annoying, because the scripting is glitched and you've got about a 60% chance of dying instantly even if you do everything perfectly. 'Tis quite frustrating.

Have you ever met Neuron ?