Hearthpwn

Post-patron nerf improved matchups against Zoo while standing its ground against many popular decks at the moment in the meta. The current meta runs way too many aggro decks and Zoo is finely equipped to deal with them.

General playstyle:

Flooding the board with deathrattles and imps and winning the game with cheap late game threats. Board control is important against aggro decks and not as much against control decks. Most of our early minions are anti-aggro while allowing us to flood more minions on the board. An important note is playing slower against control heavy classes (Warrior / Priest). It sounds counter-intuitive, but you want to get value from Knife Juggler/PO while preventing their card draws, while you can tap in early game to outvalue them by mid-game. It also allows you to set up the board so board clears are less effective (Nerubian/Voidcaller).

Thanks to Khristophesaurus Dinosaurus for the gameplay video!

Tech choices:

1. Big Game Hunter. Perfect against mysterious challenger, dr. boom, fel reaver, giants. Can also deal with 5-6 attack minions with abusive synergy. Bane of Doom is an alternative depending on the meta. I see a lot of BGH usage prior to rank 5, as Dr. Boom still runs rampant and is fairly good in warlock mirrors if they also play Dr. Boom.

2. Sea Giant. Usually cheaper decks used him if they can't get Mal Ganis but in a meta where small minions flood the board, we can play this commonly on turn 4-6. Ideally if you can play it on turn 4-5 against aggro decks you're in a very good spot. This card pretty much substitutes for Void Terror, which I feel is more situational and can come out of voidcaller, which is something you never want. The only times where Void Terror is better is on a Power Overwehleming turn with Voidcaller/Nerubian. For those who don't have Mal'Ganis, Void Terror can be a decent replacement because a PO turn gives a ridiculous amount of stats on the board.

League Of Explorer:

Dark Peddler. Preeeetty good. In the current meta it can be better than haunted creeper depending on the class you're facing. Power Overwhelming and Abusive is usually autopick. Mortal Coil is the next best. Flame Imp/VoidWalker/ArgentSquire also pretty good. Blood Imp is usually too slow. Corruption can be good against really high health taunts. The 5/5 conditional card should only be picked if you already have 5+ minions. Sir Finley is an interesting card but I'd never pick it on turn 2/3, maybe late game or if it's the only card you can pick (murlocks suck).

Mulligans:

There is a lot of combinations for early game. Some cards are always kept: Flame Imp, Voidwalker, Knife Juggler, Dark Peddler, Haunted Creeper.

Nerubian egg is not an autokeep. Playing it on turn 2 or coin turn 1 can be really bad if you don't have Abusive. I typically wouldn't waste PO on Nerubian Egg in the early game either. Nerubian is super awesome in mirror warlock matches though.

Imp gang boss is usually kept if you have a turn 1 + 2 against aggro classes. Loatheb is kept against Priests / Warriors / Mages / Rogues if you already have turn 1 + 2. Void Caller + Doomguard/Malganis can be kept against Priests/Warriors if you have at least one thing you can play on turn 1-2.

Favourable matchups:

Secret Paladins. Much of our early game counters theirs outright. Typically, people lose because of fighting for board control which is usually the purpose of Zoo. However, you don't really want to trade all the time. Knowing when to trade will only come with experience. Generally speaking, I'd avoid killing divine shield and death rattle minions first due to redemption (but priority on getting rid of the shield). And I would definitely not trade if I only have 1-2 minions on board (since you can't deal with Avenge). Flame Imp is not that good in this matchup hence there's only one in the deck. Voidwalker is much better as it can tank from a minibot and a noble sac while you can set your board up. Voidcaller is usually game winning even if you only get a gang boss up as it will do work clearing the 1/1 dudes. A game would typically progress to a point where you'll outvalue them. The owl can be saved for Tirion, but it's usually pretty good on a Kings target. Still relies on early card draws though (2 doomguards + dr. boom is very unlucky).

Tempo Mage. Very popular in ladder at the moment post-grim patron. It's important to clear their board early game even if you might not trade favorably (ie against flamewaker or azure drake). Their secrets are also mostly useless since stuff like nerubian egg and defender of argus benefits us more than them. Since they don't run silence and flamewaker can trigger nerubian egg/voidcaller/haunted creeper, we're usually favored early game and will seal the game before Antonidas becomes a threat. Sea Giant is usually impossible for them to deal with if you can get him up before turn 6. Of course, you can still draw badly and lose (mal'ganis + dr. boom + PO/Abusives without minions).

Midrange Druid. Matchup is good. It does depends on how well they ramp though. But usually we will have too much threats before turn 9 or 14HP. I'd be careful on using Implosion, since you really don't want Swipe to happen and clear everything. Nerubian is a good bait for Keeper, and Voidcaller will be game winning since it's really hard for them to deal with a Doomguard/Mal'ganis on turn 5-6.

Renolock. Matchup is slightly favourable. It's favourable for us because DemonZoo is more consistent in board control early. If they don't have Reno on turn 6 they'd usually lose. I'd be extremely careful on board trades. You don't want a turn 4 hellfire to clear your board. Nerubian is extremely good in this matchup. The matchup usually depends on how fortunate they get to board clear + Sludge Belcher value.

Other matchups:

Aggro Shaman. Matchup is slightly favourable. Much better than Face Hunter for the sole reason of having to rely on specific cards for finishers and crappy hero power. Owl should always be kept in mulligan. I've played it on turn 2 against trogg. Because they don't care about the board, Argus is typically game winning on a Voidcaller/Imp Gang/Sea Giant. Sea Giant is extremely good in this matchup as well.

Midrange Paladin. About even now, since the new Keeper is very threatening to early game boards. Still, we have really good deathrattles against board clears. It still comes down to board control, but to a point. If they use Justicar you're kind of on a timer.

Midrange Hunter. Slightly favoured. Freezing trap is marginal when you flood the board, and explosive trap can backfire with Nerubiran Egg/Haunted Creeper on board. Snake trap usually won't get proc'd unless you run into animal companion or a sludge, but you can pick up a lot of tempo before turn 5 for snake trap to matter. However, Knife Juggler + Unleashed can be game winning so it's important to trade your 1/1s while saving your nerubian egg/haunted creeper unless you have to kill an animal companion.

Face Hunters. Matchup is slightly disfavored. However, they have too many 1 health minions and voidwalker/haunted creeper/imp gang boss/juggles will clear them quickly while making more minions. By turn 4 a well placed Argus (into nerubian or imp gang boss) or Sea Giant can seal the game as you'll pump more damage than they do. I'd keep the Owl too since Mad Scientist is the only threat you are worried about. I'd say there's only time to do 1-2 lifetap max, so mulligan hard for 1-2 drops, while throwing away flame imp. Imp gang can be kept if you're going second. Argus is typically the win condition.

Control Warrior. Matchup is slightly favoured to even for us. Voidwalker is really weak here so you should mulligan it away. Haunted Creeper/Knife Juggler/Imp Gang Boss/Dark Peddler/Nerubian Egg should be kept. I've kept Loatheb on occasions as well. Play around Brawl. If you have a lot of small minions don't play a Sea Giant. Use them for valuable trades. Voidcaller is easily the MVP in this matchup as they're obligated to kill it and a Doomguard/Malganis will generate too much damage for them to deal with.

Aggro Druid. I lost a bunch of games against them so I'd say this deck isn't that consistent to deal with them. Darnassus is tough to deal with since voidwalker is bad against it and your early game doesn't have 3+ attack unless you draw into abusive and power overwhelming. I'd keep the two cards since it can help against druid of the claw and fel reaver if they play it later on. This variant of druid might be the most aggressive deck yet since it has so much ramp, charge, while maintaining high health taunts. Fortunately I have not seen them much lately.

Freeze Mage. The typical consensus is that we're a terrible matchup, I don't necessarily agree (this deck can do well against any opponent really). Freeze Mage relies on Alex and a welltimed Doomsayer to win the game. If they don't get these two things, a well placed Loatheb/Voidcaller/Sea Giant will win the game. Owl/Loatheb should be kept here. I'd consider keeping Nerubian Egg but it's typically used as an anti-board clear tool, not an Abusive/PO target. I've faced quite a few of them. It really comes down to how much ramp you have (Sea Giant + Voidcaller/Doomguard) is a lot of threat. Preventing Acolyte of Pain value is *very* important. 

Control Priest. It's a decent matchup and comes down to what you know about their deck. I've had some success playing the game slower but rushing them is also an option. I find the key is denying their draws. It's still hard because they have so many board clears and high health minions. Nerubian Egg and Voidcaller are extremely good in this matchup. Always be wary of Lightbomb and Holy nova. Dark Peddler's Corruption is also very good in this matchup. I don't mind keeping PO to kill a deathlord.

Dragon Decks. The matchup is horrible for us. Dragon Priests and Malylock are both tough matchups due to high health minions and taunts, while having more board clears. I think I've lost 3/3 against Malylock, because this deck just isn't fast enough compared to aggro zoo to do any harm before they hold control. If you see them, go on the offense and hope you don't get Hellfired. Holy Nova is a bit easier to play around but Lightbomb destroys Sea Giant - but is very good when you have Doomguard on the field.

Climbed to Legend 3 times with this deck, October 2015, January 2016, and February 2016. There was loads of Secret Paladins and Midrange Druids, all relatively bad matchups. The deck is largely consistent, but I'd say my winrate was about 60%ish (again no stats because cuz laptop sucks lol).

Overall, midrange zoolock can be a very entertaining deck to play, since you are offered multiple choices and some plays may not appear optimal or on curve but may be the best play. For example, playing Doomguard from hand even when it's not lethal to set up lethal for the next turn. Or, when to Taunt up vs. playing a Voidcaller. In the end, have fun and good luck!

I'm going to miss this deck once Standard hits.