I will go down the list on my thoughts of each card.
Goblin Raiders - I think this is a cool card for warrior in arena, because it gives Warrior a good minion to play on turn 3 and also its a great draw for late game in case you need that extra power. I wish I could see this more as a control type card where if you have 12 or more armor draw two cards. The only problem I may see with this card is they may not want to print something similar to Ancient of Lore and how they nerfed it because of the body and draw, but they also created Ultimate Infestation, so who knows...
Grounding Totem - I think is a fun card for Shaman I would say possibly raise it to three mana, because it wrecks the hope of control decks from removing it from the field, unless you play Priest and run Duskbreaker.
Shore Lurker - Right now I see this to be a very strong card in Paladin, it may not stop board clears, but it can punish your opponent for not taking care of your minions. It has some fun synergy with having your opponent needing to use two board clears in order to remove your board. Or trade some minions into Shore Lurker first to negate the effect. I feel to make it a bit less powerful, is to either make the minon 2 mana 1/1 or remove the divine shield from it (however removing the divine shield would make the minion a lot weaker overall).
Playing With Fire - It seems like a really cool card with a fun effect that punishes you if you don't use it efficiently. However it's a very powerful removal for two mana, in arena it would probably a pain seeing this everywhere, because you don't care about your health as much and you just want to make efficient trades and want to keep board control. Another positive is you didn't give it the ability to go face which is great because that would destroy Ice Bolt. All in all I think the card may need to be raised to three mana, or possibly do a set amount of damage to yourself if you use it, to give it more of a drawback.
Poison Nova - I like it, a cool midgame card that doesn't remove your opponent's board immediately. It gives your opponent's a possibility to use their minions to attack once, it's interesting with deathrattle cards and it also affects your side of the board. Personally 10/10.
Wandering Alchemist - For standard this seems pretty damn good. In arena this wouldn't be broken, but I know it would annoy the hell out of players. An excellent two drop on turn two a 2/3 seems more reasonable, but I also understand why you decided to go with a the 2/4 stats. Very powerful Northshire turn 1 and this on turn two to draw through your deck, but still a cool card.
Ranger General Sylvanna's - My only opinion on this car is possibly make this 4/5 for 5, not an overpowered card, makes weapons in Hunter a lot better, but seeing this card being more used for aggro then control, makes it annoying card for your opponent to deal with, when you play it on curve.
Karvark, the Soul - It's just a bit to powerful, normally you would look past a 10 mana 10/10, but giving the ability to gain +10/+10 every time and taunt is just crazy. Playing a deck that mills makes this card scary as hell, and plus unless you are mage who could polymorph this or it will just keep coming back. I'm not sure how to make this weaker possibly changing that +10/+10 to plus +5/+5.
The Perfect Crime - I see this as a fun meme mill card. I think the condition is powerful in that type of deck, I honestly also kinda like giving this card the effect draw a card too. I'm not sure of the power level of this, because you lose a turn by doing nothing, but it could also be really great for some cool highlights!
I hoped this helped, I like a lot of these cards, I just feel they need some tweaks here and there!