Hearthpwn

I never mentioned Giant Wasp because I thought I was making it clear, but I guess not. Giant Wasp has a chance at survival, yes, but only a chance. The Stealth is only a small piece of protection, and can be countered with AoE like Consecration. Furthermore, it can be played around. It's why Giant Wasp isn't seen in many decks; it's primary role is to be a deterrant/bait for potential threats your opponent has.

That leads to the issue with a 3-mana Poisloc: it can't be played around, at least not as easily as a Giant Wasp. Poisloc's job is not to provide board presence, but to be an answer. Rush and Poisonous provides that instant response to a big threat already on the board, something that cards like Giant Wasp cannot. It doesn't really matter if it's a minion or a spell in plenty of cases; it's a piece of removal, just like Polymorph. And the low 3-mana cost allows for plenty of mana for dropping high-value threats in late-game turns, like a Dr. Boom on Turn 10. I am well aware that such a move is not possible for Vilebrood Skitterer, and, again, it was the ENTIRE point I was trying to make. 

That's all I wanted to say, and why I feel that Poisloc really deserves a nerf. Do think hard on that mana increase nerf.

Poisloc: I still have to argue that it is precisely BECAUSE it is low cost that it is good. That's what my whole argument was about. Not every class has access to secrets, and the few that do can easily be played around (Snipe, Explosive Runes, Autodefense Matrix, etc). While a few decks may not have the space for this card (maybe like Exodia Mage or something, I dunno), I feel like a neutral single-target removal at such a low mana cost is too good to be printed. Remember: Druid lost Naturalize due to the class supposedly not being able to be good at single target removal, according to Blizzard. At 3 mana, it is on par with cards like Shadow Word: Death, a class-specific single-target removal card. It's (arguably) better than Polymorph and Hex too, both class-specific single-target removal that cost 4 MANA. And since it's a NEUTRAL card (and therefore available for every class), plenty of decks will want to use it. 

The card may still be salvageable at 4 mana, though I would keep a very close eye on it if it was ever printed in Hearthstone.

The two cards I have issues with:

Poisloc: That is one potent source of removal, and probably why we've never seen a Rush Poisonous minion at such a low cost. Compare it to, say, Voodoo Doll or that Hunter-specific Vilebrood Skitterer. Both of these come with conditions (the first taking extra time/mana to activate its deathrattle and the other being a hunter-specific on top of having such a high mana cost). Even something like Toxmonger takes at least 5 mana to play and requires two cards to get a poisonous rush minion. Simply put, this card is way too good for Hearthstone, especially since it's a neutral, and requires a nerf. 

Isaiah, The Shining: That is one powerful hero card, perhaps even on par with Bloodreaver Gul'dan, hailed as the most powerful hero card in Hearthstone. First, there is the 7 armor. Why 7 armor? Just make it 5. Second, the deathrattle is essentially an Ice Block and Time Out!, AND, once triggered, provides access to a very powerful secondary hero. We've all seen Malfurion the Pestilent's power with his amazing versatility to see just how powerful versatility is. His hero power provides what is essentially The Silver Hand, Tank Up!, and Dinomancy for all minions. Three very powerful hero powers, and we can choose any of these at our leisure. And finally, I'd like to point out a powerful combo this card can use. Specifically in Wild: Reno Jackson and/or Forbidden Healing. Just heal back up to full, and all's well and good. And YES, you CAN target Immune characters with healing abilities (I checked via the wiki). Tl;dr too powerful, may even be unsalvageable.