I just hit rank 1 legend with this list created by my friend Tryndamere. The list is perfect in my opinion so I figured I'd share it.
First of all, zoo is a control deck, not a rush deck! You win by gaining early board control and making efficient trades every turn! Cards like abusive servant and power overwelming help you do that. Always play around the AEO removal from the class you are facing, like consecrate / Swipe etc. Of course this is elementary knowledge, but it is the most important thing to do.
Easy matchups: Mage (mech), shaman, priest, paladin, druid,
Mage: Against (mech)mage look for a good curve and just keep trading with all the mechs and you will win easy.
Paladin: Always play around consecrate obviously, narubian egg is a very good counter against consecrate.
Hard matchups: Warrior (Grim Patron), Warlock (Handlock), hunter (Face), Rogue,
Warrior (Grim Patron): Very difficult matchup when they have early board clears, Just keep clearing and suicide off your own small minions so he can't get value from charging Grim Patrons. Winning board control is always key to winning the match with zoo.
Warlock (Handlock): This is one of the hardest matchups, just try to get him down to 15health by turn 5 just above molten giants range and hope you draw into power overwelming/Doomguard as the finisher.
Hunter (Face): Always keep Defender of Argus in the opening hand, it is key to winning the game. When you managed to argus something like Imp Gang Boss [/card]+ [card]narubian egg, consider racing the hunter and going face.
Rogue: Don't pop your narubian eggs too soon, it is a good ensurance against Blade Flurry. This is a really hard match, but if you manage to play Loatheb while having a board, you win. Power overwelming is great for trading against rogue minions like Violet Teacher and Azure Drake.
* Power Overwelming is good against most classes
* Imp Gang Boss is always a good turn 3.
* Big Game Hunter Saved my ass so many times. It is the reason I managed to get Rank 1.
* Loatheb Closes out games when you are ahead.
- Loatheb + Dr. Boom
- flame imp + Sylvanas
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