Worst deck ever? I don't think so. I'm still working on it, but it's quite good now. I'm playing mostly on ranks 5-3. Maybe when I get myself enough dust to make big Priest or Pirate Rogue, I will try to compete in the Legend rank to have some proofs that it's really good (I'm thinking about clips with salty streamers losing for example to the Bloodlust and Electra Stormsurge combo - haven't seen one yet, but maybe some day...)

Saviours of Uldum tests finished! Quest (and the whole deck) turns out to be pretty bad against the omnipresent Secret Mage. Although on the other hand, Plague of Murlocs, the second card that seemed interesting is quite good against all Reno decks (especially Renolock) and crazy good against Big Priest. I'm going to take a short break from this deck so that i can enjoy playing with my collection of Reno decks

Latest performance: 2-1 (20.08.2019), playing with the new Quest instead of Hagatha's Scheme currently

Wins: Quest Reno Priest, Quest Druid

Losses: Linecracker Combo Druid

You can skip this part, it's just a score live record of a man without decktracker

Overall score: 43-22

Losses:

• 5 - Zoolock (4 Healzoo and 1 "Good old Zoolock")
• 3 - Big Priest
• 2 - Big Druid
• 2 - Star Aligner Druid
• 1 - Midrange Hunter
• 1 - Renolock
• 1 - N'Zoth Rogue
• 1 - Tempo Mage
• 1 - Pirate Warrior
• 1 - Odd Rogue
• 1 - Even Shaman
• 1 - Pirate Kingsbane Rogue (the cancerous one)
• 1 - Odd Paladin
• 1 - Linecracker Combo Druid

Wins:

• 7- Odd Paladin
• 4 - Odd Rogue
• 4 - Big Priest
• 3 - Renolock
• 2 - Mech Hunter
• 2 - Spiteful Priest
• 2 - Mill Rogue (without Kingsbane) 
• 2 - Even Shaman
• 2 - Zoolock
• 2 - Shudderwock Shaman
• 1 - Big Shaman
• 1 - Tempo Mage
• 1 - Burgle Rogue
• 1 - Odd Mage
• 1 - Mecha'Thun Priest
• 1 - Star Aligner Druid
• 1 - Midrange Hunter
• 1 - Even Warlock (on 1 HP left)
• 1 - Even Reno Warlock
• 1 - Murloc Paladin
• 1 - Quest Mage
• 1 - Quest (New) Druid
• 1 - Quest (New) Reno Priest

Replacements:

1.This deck differs a bit from its version from Hearthpwn. I've realised that Gluttonous Ooze isn't necessary here and The Storm Bringer is being changed to 6 mana soon. So, those 2 cards are out and Sludge Slurper goes in. (Thrall was the second card to be thrown out before, but it does a better job than Ooze as it synergises with cards like Fungalmancer or Giggling Inventor, so if you don't want to run Hagatha's Scheme you can easily put Thrall instead of it).

2. List of cards you can put into my version of this deck. I don't recommend replacing more than 3-4 cards, but if you don't have for example Loatheb or Electra Stormsurge, you can replace them with one of the following cards:

Shaman cards: Feral Spirit, one Hagatha's Scheme Far Sight (instead of Mana Tide Totem), White Eyes, Thunder Bluff Valiant.

Neutral cards: Gluttonous Ooze, Master of Ceremonies, Dr. Boom, Azure Drake, Elise the Trailblazer, [Hearthstone Card (Zillax) Not Found], Tar Creeper (instead of Stonehill Defender if you meet more Aggro than Control decks). 

3. I've recently realised, that Bloodlust does such a great work that I'm even considering putting a second one here. If anyone likes experimenting, you can do it, although I personally think that it would do nothing most of the time because of no minions on board and would be a pretty bad topdeck.

This list will be expanded as soon as I find some other cards which are really good in this deck

Keep in mind that most of the examples written here are just experiments and I've never tested any of them except Tar Creeper (and all card draw ones)

Mulligan Guide: Coming SOON!

Tech Guide: Coming SOON!

Matchups: 

Overall Best - Odd Paladin (7-1)

The best matchup for this deck, as you see, is Odd Paladin. Why? With Fire Fly and Healing Totem played on turns 1 and 2 you stop the whole early pressure from  Silver Hand Recruits, it's also nice if they are followed by Tar Creeper or Stonehill Defender on turn 3. Also, if you have Corridor Creeper on your hand, you can use your Evolve or Unstable Evolution early. You also have cards like Lightning Bolt or Lightning Storm which totally counter this deck (Wrath of Air Totem combined with Lightning Bolt to delete Raid Leader, Warhorse Trainer or Steward of Darkshire and Lightning Storm to delete the army of Recruits, even those buffed with Level Up! or Quartermaster).

New Best: Not known yet, probably Big Priest (4-3)

I think that [Hearthstone Card (this deck just needs Plague of Murlocs to increase its winrate, at least against this beloved and highly respected Priest deck. It's not the best match-up as I initially thought, but may become one once I slightly rebuild this deck. Anyways, I'll leave the guide below

New great matchup? I've returned to this deck recently and since Big Priest is one of the best performing decks right now, i've faced him in 5 out of 14 games (only counting last month) so far and I won 4 of them (my first loss against Big Priest was when I didn't have Loatheb; it was about half a year ago). Let's look how can we beat it. The main win condition here is Bloodlust - you build a board of small minions, then you play Loatheb, followed by Bloodlust in the next turn. Obviously, you have to avoid the situation, somehow, when your opponent builds a wall of Obsidian Statues. If your opponent rolls Ragnaros the Firelord, Archmage Vargoth or Ysera (although it's kinda bad when Ysera rolls Ysera Awakens) try not to kill them to make your opponent's resurrection cards useless. You can consider killing Vargoth before your opponent gets to 6 mana, but only if it doesn't cost you too much.

Overall/New Worst - Secret Mage

Odd Shaman has completely no healing cards and it's impossible for it to deal with the heavy burst coming to your face. Secrets totally ruin your early-game plan which is to build a decent board. Even if you manage to do that, your cheaper minions (including Taunts which are meant to stop at least a bit of damage from Kabal Crystal Runners and stuff like that) are very likely to perish in flames of Flame Ward

Old worst - Heal Zoolock (0-5 before, now 2-5)

(Not that much outdated since the new Wild Zoo version has come out and occupies a spot in Tier 3)

The worst matchup for this deck is Zoolock. 5 games lost (very fast) and 6th won on 1 hp left. Just one game won with no problems. Why? Simply because Odd Shaman has too low amount of board clears to delete 3-4 minions each turn, and you have no early game minions which are able to deal with Flame Imp or [Hearthstone Card (Happy Ghouls) Not Found]s put on board on turn 1-2. Really nobody plays with any kind of Demon Zoolock, everyone plays with Healzoo, using no cards from Wild in it. Demon Zoolock with an army of Imps,Darkshire Councilmans and Knife Jugglers would be much easier to stop Demon Zoolock is more popular on Wild now, although I still don't face many of those.

This deck's worst flaw was always the fact, that it was unable to delete big minions while you were losing board. It was an automatical loss against any kind of Big Druid decks (although, surprisingly, it performed not so bad against Big Priest). The new card, Plague of Murlocs deals with this problem very well. Lack of healing turns out to be the real problem now.