Hearthpwn

I had a Warlock quest, so threw together a discard/demon/DK Guldan deck. And it's winning consistently in Casual. (Even though Guldan hasn't shown his face in 6 games)

No, I'm not stupid enough to think it's a viable deck for ladder. Just find it funny that it's more successful than a lot of decks I've carefully crafted.

What decks have you had that happen with?

"all taunt" 

just because I was sick of losing to aggro.  I don't care that every other deck crushed me but I'm pretty sure that (at the time) I was beating aggro decks 100%. 

Just had druid quest and the 75 murloc quest at the same time. Put lots of murlocs + the cheap new druid taunts, mark of the lotus and power of the wild in a deck. Went 5-0 and finished both quests in 5 games.

Played a 6th game after quests were done and came up against a token druid deck that played double flappy bird turn 1 to remind me my deck was not a real competitive deck.

rogue mill c'thun. makes quest mage, highlander priest and big priest eat their shit but gets trampled by aggro and jade druid.

I did pretty well with an all overload deck.

 during Un'goro i wanted to try Big druid using The Curator package, but i don't have any Deathwings, so i yhrew a copy of Blood of The Ancient One, Tyrantus and Faceless Manipulator in the deck as replacements, then i got a second copy of Blood of The Ancient One and Giant Anaconda  during the great legendary glitch so i adjusted accordingly , once Kft came out i adjusted it yet again so that i could use Spreading Plague  and Ultimate Infestation, plus i replaced Ysera for The Lich King since she's so not worth it without being able to cheat her with deathwing, and go Figure, the deck actually became consistent, i summon The Ancient One in 4 out of 5 games and in games where i'm palying against a class with too much ahrd removal i just Faceless Manipulator a Tyrantus.

i Called it: Flora's Ancient Power.

Edit: I'd point at the deck at my signature but it wasn't exactly a throwaway deck since i was actually trying to "translate" Murloc Paladin into Demon Warlock using kind of the same theories the Murloc Pala deck uses.

I remember making a Malygos Hunter back before the last standard rotation and it did better than you'd expect. It was also really fun.

I did quite well with an all taunt except Reno Jackson and Armoursmith warrior to do a taunt quest, had a winstreak completing the quest.

My best one was the no minions costing less than 3 deck which I still play now when I get a priest quest or have the 40g play minions costing 2 or less quest, it's become more like Big Priest these days, but for wild. Still need another Eternal Servitude and Obsidian Statue to improve it though. Only cards I crafted where the obvious first ones when I started, Ragnaros and Sylvanas, all the other legendaries jammed in there were from packs or adventures.

EDIT: I have similar one on my US account, but don't have Y'Shaarj or Kel'Thuzad, nor an Obsidian Statue, but I did open Deathwing and Ysera and added a Free From Amber and that did well today at rank 15 in wild for a priest quest. No one expects the Deathwing unless they see a 1/1 from Barnes ;) They usually kill it and I resurrect a 12/12 though.

Bump with a replay https://hsreplay.net/replay/8gvomRMRESUSXoJwzbAsrj

Quote from cordobatim >>

I had a Warlock quest, so threw together a discard/demon/DK Guldan deck. And it's winning consistently in Casual. (Even though Guldan hasn't shown his face in 6 games)

No, I'm not stupid enough to think it's a viable deck for ladder. Just find it funny that it's more successful than a lot of decks I've carefully crafted.

What decks have you had that happen with?

Divine shield paladin that i made just to finish "tiny bubbles make me happy" as fast as possible. No bolvar, just 95% divine shield minions, two blood knights and a weapon or two.

No seriously i win a lot every time i get that quest, don't understand what makes it work so well.

I was surprised, and pleased, to see several types of decks I've made to do quests or just fool around with in casual be listed by others.

Like the OP, I made a discard Warlock deck because I pulled the quest and figured might as well. It wasn't great, but won a few here and there. I also made a divine shield paladin deck similar to what Pandabird said. It worked surprisingly well!

I also tried making a few iterations of a Druid quest deck, since I also pulled that back when Un'goro came out. It would either do great or be steamrolled quickly, but the games were fun.

i recently had loads of fun and was actually doing very well in casual w/ a burgle rogue w/ voss and gallywix. used unstable ghoul + plague scientist as anti-aggro/board clear (which people often played right into). the deck felt like it was two slots away from being tier 2.

i also recently had a druid card quest. threw 30 randomish strong druid cards in with little thought of synergy or composition. it was wayyyyy better than it should have been.

Every time I build an All-Paladin-cards deck to complete that quest, it ends up doing pretty well. Paladin has some tough class cards.

getting some streaks with my Control DK mage. 

I just wanted to make a deck with all the discover cards. It worked out pretty good actually.