Class: Warlock
Card type: Minion
Rarity: Common
Mana cost: 1
Card text: Whenever you discard a card, draw a card.
Attack: 1
HP/Dura: 3
Other notes: Demon
Remmeber that REALLY stupid mill yourself deck totalbiscuit did a while back? Yea this is bassicly "mill myself" the card. It has some uses like negating the effects of cards like soul fire, but for the aweful Attack/health and the fact it will never be played on curve means I doubt this card will see competitive light.
Class: Neutral
Card type: Minion
Rarity: Rare
Mana cost: 6
Card text: If you're holding a Dragon, destroy an enemy minion with 3 Attack or less.
Attack: 3
HP/Dura: 6
Other notes: Dragon
Firstly, Blizzard you will never live down that pun.
Otherwise, this seems like a very well balanced card. It has a similar effect as stampeding kodo but with the benefit of targeting the minion as well as triggering other dragon effects. The attack leaves something to be desired but if it clears one minion and takes out a few lower cost ones(Malchezaar's Imp) then your getting value.
Class: Neutral
Card type: Minion
Rarity: Legendary
Mana cost: 3
Card text: Stealth At the end of your turn, summon a 1/1 Steward.
Attack: 1
HP/Dura: 1
Other notes: Steward is a vanilla 1/1 - Blue source
Zoolocks dream, the stealth means it must be aoe down or get a lucky ogre swing. The major downside is losing a strong turn three, and if your playing against a Mage then this card isn't going to be doing much. But in control match ups you can get immense value from this one minion if your opponent can't remove it.
Class: Mage
Card type: Minion
Rarity: Rare
Mana cost: 1
Card text: Battlecry: Add a random mage spell to your hand
Attack: 1
HP/Dura: 1
An odd filler card, I can see it being used in a freeze Mage deck where you don't have a strong turn one anyway but short of that its just another random effect to add to the pile.
Those are all the ones currently on the r/ competitive hearthstone list, so I know I missed a ton but that should give you an idea of my thoughts right now