Hearthpwn

This is a relatively fast deck that tries to either rush face quickly and then finish off the game with high damage stealth minions and swipe. You will also need to make valuable trades and plays to try and keep ahead on the board. It really just depends on what deck archetype you're versing.

Mulligan: Don't keep any spells except for Innervate(Only keep 1 max). Don't keep any cards that cost 4 or more. Keep all beasts that costs 2 or less except for the Ravasaur Runt and Stubborn Gastropod. Only keep 3 mana minions if you have a proper curve into it.

Cards Explained:

• Stubborn Gastropod is in there not only because it is a beast but because it does really well in situations where you lose the initial board control of the match or where your opponents plays big minions. It is actually quite a diverse card and come in handy a lot.
• The Coldlight Oracles should be play when you really need a quick boost in card draw or it is your only play for turn 3. Try not to play it against other aggro deck as it might help them to get the cards they need to burst you down or win the board.
• With the Elder Longneck, you typically want to adapt with the +3 Health, Stealth or sometimes on rare occasions even windfury. It is a strong beast with a high attack stat and can be a very valuable minion in obtaining board control or finishing off your opponent.
• Vicious Fledgling is a game winning card. It can snowball so easily with its ability to adapt several times and gain stats rapidly as the game progresses. For example, you could run him into your opponents face, adapt for windfury before adapting again and then next turn you could adapt twice again and so on. If this card is not killed instantly it becomes a large threath easily and if it is killed immediately it would usually have to be a trade in your favour because of your opponents desperation so it is a high value card.
• Savage Roar Is usually going to be used to finish off games or whenever you have lots of minions on the board and can get a lot of value out of it. It works well when used after playing stealth minions like the Jungle Panthers because they are almost guaranteed to survive the turn and recieve the temporary bonus attack.
• With the Verdant Longneck you will have to debate whether you play it or the Stranglethorn Tiger on turn 5 in hope of using the Menagerie Warden. You should decide whether it is worth the risk of maybe getting a good adapt so you can summon a copy of it or the reliable Stranglethorn Tiger.

Replacements:

• Mark of Y'Shaarj can be replaced by Mark of the Wild although it will be noticeably worse because of the loss of card draw, however, it can be game-changing in some matchups because of the taunt.
• I would replace the Vicious Fledglings with the Ravasaur Runt but it is much worse in just about every way so I highly suggest just crafting the Vicious Fledgling.

Changes: 

• Swapped out Loot Hoarder for Wrath because it offers draw and a way to kill enemy minions in the early game.
• Swapped out an Emerald Reaver for Leeroy Jenkins so that tou have mroe burst and another activator for Elder Longneck.

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Good Luck and Enjoy! :D