Hearthpwn

Treason, Then: 3/5. Rogue board clear isn't really a thing, and it's pretty imbalanced I think (I put it at least above lightbomb on average), given that it can be prepped. Neat idea though.

Explore Zangarmarsh: 1/5. It's just a better explore un'goro. Kind of boring.

Antonidas's Servant: 1/5. I would rate this higher, but it is obviously completely broken with arcane missiles, frost bolt, or flame geyser as one sorcerer's apprentice allows for an easy OTK.

Idol Worship: 2/5. It's a lot like Explore Un'goro but it fixes a huge part of the problem with it with the draw. 5 mana draw 3 cards >> 2 mana do nothing.

Ambassador Gallywix: This is my card.

Farseer Nobundo: 2/5. It is strictly better than Skulking Geist and Eater of Secrets, both of which are almost always one-ofs, except your opponent knows the card. In those situations, 3 mana 3/3 draw an important card is way better. I'm not sure if it's better than golakka crawler but you could certainly run 1 golakka + this instead of 2 golakka crawlers. A 3/3 that occasionally has to discover a vanilla 2/3 is just as good as a vanilla 2/3.

Plated Ferrosaur: 4/5. If you damage it twice it's a 5 mana 4/3 with an effect that nets you 2 iron hides and your opponent 1 (probably). That sounds pretty good. It does require some setup to work in your favor, instead of your opponent's, so I'm glad the cost isn't any higher than 5.

Blast from the Past: 1/5. A strictly worse ragnaros, except it has spell synergy. Seems unoriginal to me and I don't understand why it has an elemental requirement instead of something else.

Gorilla Goon: 3/5. I'm not sure if it's balanced but it seems appropriately flexible. Obviously not a 1-drop, but it can be used if you're fighting for board control in conjunction with other minions to get better trades. Or it can go face. Maybe a 3/1 is where it's at, but the flavor would be weaker in that case.

Crystal, Mana's Jewel: 3/5. I don't think that getting a mana geode is much different than getting a 2/2 crystal unless you have some crazy combo set up with wild pyromancer and circle of healing. That said, this seems pretty balanced to me.

Cuteness Overload: 2/5. I will give it an extra point because it did get the memes right.

Get Him Boy!: 3/5. The problem I have with this one is that your opponent often won't be able to reduce the damage from 5 to 3 by killing your beasts, because attacking with any minions will activate the secret. I do appreciate that the damage is variable, though.

High General Turalyon: 1/5. Who thought this one was a good idea? You have to damage him 4 times to destroy him, or twice while destroying another minion, in one turn. Or you have to leave him up without divine shield and damage him 3 times, or once while destroying another minion. Either way it's ridiculously inefficient for the opponent. And if he can't deal with the minion initially it can spiral out of control.

Crusty Cook: 2/5. So... aggro decks are not going to run anti-tech cards. That doesn't really make sense. Control decks would rather just run the tech cards. Where does this guy fit?

Argent Recruiter: 3/5. Comparable to Justicar Trueheart. Not much to say about this one.

Stormwind Librarian: 2/5. It's kind of like burgly bully except I think you'd rather have the coins, and 4 health is a lot easier to kill than 6.

Dullahan, the Headless: 2/5. The idea is pretty far out there. I can't really imagine ever playing headcrack in a deck where you'd want lifesteal. The random enemy part makes it sound like a board clear, which again goes completely against the purpose of headcrack. Are you just hoping to waste a ton of mana before eventually playing this 9 mana minion?

Throat Slitter: 0/5. Obviously beyond broken.

Grem Hackheart: 3/5. It's funny but I could actually see this making pirate warrior. If the cost is reduced in your deck, does Keleseth work?

Manboarpig: 2/5, unless this works with call of the wild, then 3/5. I'm not generally a fan of cards that control RNG like this.

Edit: Linking cards since multiple ones are referenced.

Grimestreet Informant

Kabal Courier

Lotus Agents 

I'm struggling a lot against aggro decks, particularly hunter and most of all tempo mage, do you have any tips for dealing with them?

Terrorscale Stalker: 4. Pretty decent card if you can get a deathrattle, bad if you can't. On average, you won't. Obviously somewhat draft dependent. 

Thunder Lizard: 3. I could see this being part of a very dangerous curve if one class gets a good elemental for turn 2. Pyros doesn't count, and I can't think of anything else.

Lightfused Stegodon: 3. Sorta hard to see this being terrible. At worst it is slightly worse silver hand recruit + keeper of uldaman, but you'll almost never keep multiple silver hand recruits on the board unless you intentionally keep around that 1 mana spell.

Hemet, Jungle Hunter: 2. Since most games don't go to fatigue, this is a great arena option for upping the consistency of your late game if you're playing an aggressive or midrange deck.

Blazecaller: 1. I assume that you'll be drafting enough elementals, since their synergies look quite good and there are going to be a reasonable number of them. This effect is way better than Thunder Lizard and it comes down later, so you're more likely to be able to play an elemental.

Servant of Kalimos: 2. Some elementals are quite bad, but this on average will give you an excellent choice, and you'll often be able to play it + synergies the next turn.

Ravenous Pterrordax: 4. You basically have to kill an imp or a bad one drop for this to actually be worth it, and Imp Gang Boss is rotating out of standard.

edit: how do you include the card links effectively? I'm new here.

Ratings of 1: Swamp King Dred, Crackling Razormaw, Pyros, Tortollan Shellraiser, Vilespine Slayer (this card needs a new category for it), Kalimos, King Mosh, Molten Blade, Blazecaller, Tol'vir Stoneshaper, Volcanosaur, Tar Creeper.

Ratings of 2: Verdant Longneck, Raptor Hatchling, Tol'vir Warden, Arcanologist, Flame Geyser, Sunkeeper Tarim, Crystalline Oracle, Stone Sentinel, Volcano, Elise the Trailblazer, Gentle Megasaur, Glacial Shard, Hemet, Servant of Kalimos

Ratings of 3: Living Mana, Dinosize, Lightfused Stegodon, Mirage Caller, Fire Fly, Gluttonous Ooze, Golakka Crawler, Thunder Lizard.

Ratings of 4: Terrorscale Stalker, Mana Bind, Hydrologist, Lost in the Jungle, Lakkari Felhound, Clutchmother Zavas, Explore Un'Goro, Primalfin Lookout, Ravenous Pterrordax.

Ratings of 5: Sherazin, Corrupting Mist.