Wait a second, that WORKED?!

[Yellowbeard]

Jedi Knight: Mysteries of the Sith.

I spent ages fighting Kyle Katarn before I realized he was genuinely invincible and all I had to do was turn off my lightsaber at the beginning of the fight.

 

[jakefongloo]

First time my friend told me you could strap C4 to a UAV in BC2 and take out objectives.

Can't remember any...wait, wait! Got an OLD one!

Baldur's Gate 2, there was an optional Dragon you could fight, Firkrag, who dropped the best sword in the game, The Holy Avenger. I couldn't beat him with my party, and I didn't want to leave the guy unharmed with me, no matter how underpowered I was. Was playing a mage, ran out of all spells other then "Flesh To Stone". That thing fails on most NORMAL guys...it worked, and the sword somehow was not destroyed like most items are.

Luckiest...roll...ever...

Could always just set a shitload of traps around it/him/her before talking to it/him/her. Traps bypass any resistances. Traps stay indefinitely so you can lay a bunch, rest, lay a bunch more...etc. Works best with I think the bounty hunter class...as they get Special Traps which deal about 3 times more damage.
Kinda cheap....but that fight is nearly impossible any other way.

Lol yah have yoshimo set his traps around the dragon, dual-class him, cancel, and he gets his traps back. Set about 25 of the bastards around and attack him for a fun time. A .26 second boss fight is always fun to watch.

 

[Planetoid]

Also not so much of a boss fight, but once in GTAIV I had evaded the cops long enough to get back down to a 1-star level, and at that point I was in the red and ridiculously close to death. A pair of cops were still chasing after me on foot.

You know those films where someone who is being chased evades capture by darting around a corner and hiding behind something? I ran into an alley, found some garbage cans on someone's back porch, and crouched behind them. The cops who were following me turned the corner and RAN RIGHT PAST ME. I was so shocked that it worked I emerged from cover and watched as they continued to run down the alley and around the next corner.

Not wanting to waste time, I doubled back down the alley and stole their cruiser. To safety!

 

[timeadept]

Ah, i remember one from AssCreed one now. I think the guy was Robert de Sable well

Spoiler: In case you have yet to play the first game and still want to

You fight through waves of soldiers on the battle field and then fight off at least 10 guys at once right before dueling Robert. Anyway it took me 3 tries to get through all his men, then on the 3rd attempt Robert steps up and i counter his first attack, knock him to the ground and run up and stab him.

Also in AssCreed one

Spoiler: Final Boss

I manage to get to phase 3 of the fight on my first try but it wasn't easy. So the guy vanishes and i start freaking out and end up climbing stuff to prevent him from appearing from thin air behind me and attacking me. After about a min it becomes clear that i need to look for him, i see him off in a corner of the garden and sprint at full speed right at him, tackle him to the ground and then stab him.

and all i could think was that was it?

 

[internetzealot1]

In Gears of War, I couldn't beat RAAM until he got stuck on a wall. Also, meat-tornado Wesker from RE5 + RPG = shitty climax to shitty game.

 

[WanderingFool]

My bit of brilliant thought. I was playing oblivion, and while playing as my magic user (with little health and magic left) I had three guys chasing me. I was in one of the ruins, and by shear chance, realized I was in one of the rooms with the floor trap (the one where when you step on it, it rises up into the ceiling). I manage to jump across with out landing on the floor, and when the three enemies stepped on the tile, boom! I win.

 

[ultimateownage]

Fable 2 boss.

Spoiler

*shoots him once* *he dies* Wow, fucking really? I was just doing that because it's obligatory to do a dramatic and pointless starting shot.

 

[BanthaFodder]

GTA IV
I spawned in the hospital, beat everyone in the waiting room to death with a baseball bat except for one guy. he tries fighting back. I'm in the red and the cops are coming, so I run to my ferarri outside before they arrive. I speed away, crash, and wrap myself around a lamppost. somehow, the SAME GUY caught up on foot and started beating me up.
*police siren*
cops show up, arrest HIM, drive off. I proceed to push an old lady in front of their cruiser. they do nothing.

 

[Rayne870]

After fully a few years of really enjoying Skies of Arcadia on Dreamcast I recommended Skies of Arcadia Legends on GC to several friends, eventually I got my own copy. It took me 2 encounters with that bounty hunter that chases you before I figured out I could put her dog to sleep and just nuke the hell out of her.

 

[Beastialman]

Pokemon Emerald, Norman and his Slakings. Never knew you could protect/detect on the first turn, attack when it's slacking off, then protect again thus never hurting your pokemon.

 

[Christopher Dudgeon]

Final Fantasy 7...Ruby Weapon

Could never beat him as he would remove my 2 companions before i could start hurting him then i took a risk by killing my companions before the battle started and what do you know he sticks his hands in the sand straight away and then cast phonix downs to revive the other 2 and then hades to paralyze him and then hammer away with Kinghts of the round and mime it till he's dead.

I then took my reward and got it exchanged for...... A Bloody Golden Chocobo of which I already had one as I needed it to get Kights of the round.

Took me nearly 24 hrs to create a golden one so I was mightly pissed off when I got a second!

 

[CarpathianMuffin]

The mouse boss in Recettear. It kept healing itself with mushrooms, and I was barely whittling away at its health, so I was getting frustrated. It took me seven minutes before I realized that eating too many mushrooms, or the purple ones, I forget which, would make it fall down, left prone to hits. After that, I killed it in 45 seconds easily.

 

[Blights]

Tales of Vesperia: Every enemy or boss. Rita Mordio. Overlimit. Enough said.

TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE TIDAL WAVE.

Gusios was mah *****.

FFXII, I guess. Against one of those Judge guys, only Penelo left, no other options. QUICKENING GOGO. Insta-kills him. My fist pump was heard throughout the land.

 

[Casimir_Effect]

Done various things like this:

Diablo 2 bosses could often be made easy through skillful use of Mana Potions/Steal, Guided arrow and hiding behind walls/columns. With any luck the boss gets stuck somewhere he can't hurt you and you can bounce arrows at him until he dies. Very good for Mephisto and his Council.

DA: Awakenings - the Queen of the Blackmarsh. When she goes into her alternate form to heal, kill all the wisps but one then paralyze it while beating on the defenceless Queen.

I Disintegrated Iyachtu Xvim in Icewind Dale 2 once just to see if it worked - it did. Finger of Deaths the black dragon in Baldur's Gate 2 once as well.

Eternal Sonata could be completely broken by giving a certain character certain items, meaning hundreds of thousands of points of damage could be dealt in one characters round. Made all the final bosses very simple to beat.

Used the Kain in Mass Effect 2 on the end boss and the end fight on the derelict Reaper. Made both very easy in a great way. It was like my Sheppard had just fucking had enough so busted out the nuke launcher.

 

[strangemoose]

killed final boss in JC 2 by accidentally crashing a car with a oil tank on attached to the back on it

 

[Chris646]

Probably the geno whirl thing in SMRPG.

 

[Rayne870]

Metal Gear Solid 3, tossing out my rotten food during the fight with The Fear. I was very surprised to see him gobble up my discarded junk and essentially kill himself with a belly ache.

 

[Austin Howe]

Like 1000 JRPGs where the boss dies when you heal/resurrect him.

Considering those bosses are always undead, it's more a matter of intuition and at this point it's a sort of in-joke for fans of teh genre. The only time it was made apparent to me was fighting the salt lake boss in FFVIII, and that's the second or third undead boss the game throws at you.

 

[James Joseph Emerald]

Can't believe this wasn't mentioned before now:

Spoiler: Metal Gear Solid

Getting raped by Psycho Mantis repeatedly until my cousin comes in and tells me to switch controller ports. "That's the stupidest thing I've ever heard," I say. Another few times getting pwned and I try it. "No freakin' way!"

Also, similarly:

Spoiler: Metal Gear Solid 3

Assassinating an unarmed The End when you first see him, as he frantically tries to wheel himself away. Cruel, funny, unexpected. Couldn't believe it worked.

 

[Atmos Duality]

While not pertaining to "bosses", that sort of "WHAT THE FUCK, THAT WORKED?" response made me think of the old King's Quest series.