Priests have a lot of healing effects and not that many damage-dealers (although Dragonfire Potion is pretty good), especially when compared to Warriors and Mages. With Soraka, Pyroblast changes from a 10-Mana "deal 10 damage" to a 10-Mana "restore 10 Health" (compare to Greater Healing Potion).
Akali's text should either be "All other friendly minions have Stealth" or Battlecry: Give all other friendly minions Stealth", depending on wether you want a Battlecry or a permanent effect.
In Bard's text, replace "invulnerable" with "Immune".
In Elder Dragon's text, replace "Dragon monsters" with "Dragons". Also, since it's a very strong effect, I'd suggest lowering either the Attack or Health by 1. Compare to The Mistcaller (and also remember that he is terrible).
Heimerdinger's upgraded Inventions should cost way less. Compare Hextech Rocket Swarm to Consecration. In order for those spells to be equally or more desirable, they should cost (4) or less. I'd go with (3).
In Lightning Grenade's text, it says "stun 3 random enemies". The word "stun" doesn't exist in Hearthstone vocabulary, so I'd suggest going more into detail.
Zed's text goes over the Attack and Health bar.
That's it, only a few things to sort out. Otherwise, I quite like them. Good job.
Development history. Originally, I made Fiddlesticks a Warrior-class 7-Mana 6/6 with "Battlecry: Summon two 1/1 Crows." Crows were like Boom Bots. After talking to a close friend of mine who is familiar with League of Legends, I realized Gangplank would be a better fit for the Battlecry. So that's how Fiddlesticks became what he currently is. Possible rework: removing the Demon tag.
Something for Overload Shaman. That's it.
Somebody's hungry. Works good in and against Paladin.
I really wanted to call the minion he summons Daisy, like in the actual game. I couldn't find any good artwork for Daisy. The best I could find doesn't look too bad, but my OCD-ness didn't let me finish the card so I just called it a Golem, and made Daisy the name of the choice card that summons it. The various choice cards and summoned minions are shown below.
A guranteed last chance. I gave him 5 Attack even though it doesn' matter because of his effect. The only reason for that is so he doesn't suck if Silenced.
Probably the weirdest one I made. He's both good, bad, awful, overpowered and meh, it all depends on what minions you have in your hand. Chillwind Yeti? Good. Flame Imp? Really good. Wolfrider? Nothing's changed. C'Thun? Awful. Because Tryndamere Silences minions immediately after they're played from your hand, their Battlecries don't trigger. Handbuffs are also Silenced so that this minion doesn't become the new bane of existence for every player on ladder. Possible rework: Health.
I don't really know how to balance her, I hope this isn't too overpowered in Rogue or Mage. Though, I could see those two classes making use of this the most. Then again, Flamewreathed Faceless annihilates this. Possible rework: general balance.
A minion version of Curse of Rafaam, with the spell produced having more drawbacks to being played than Cursed!.
Rouge hasn't had a really good Legendary in a while now, so why not a mechanic-breaking one? This might even make Rogues play Justicar Trueheart, because they'll get a 3/2 weapon with their Hero Power.
A minion that gets Armor, every Control Warrior's dream come true. Kinda good in Druid and maybe Mage as well.
Cards like Shrinkmeister and Pint-Size Potion give minions lower Attack only for one turn and cards like Aldor Peacekeeper set Attack to a certain number. What if there was a card that can make a minion have 0 Attack and make it almost worthless?