Hearthstone: Good cost minions, but with downsides? [closed]

Here are some, I will be adding more in. Warlock has a lot of cards like this, but there are some neutral or other class ones also. It's hard to pick cards without a definition of downsides. Oasis Snapjaw is a low cost minion (4 mana) for 7 HP, with the downside of having only 2 Attack.

Here are some of the ones that come to mind, sans the ones that you already mentioned (Flame Imp, Arcane Golem, Leeroy Jenkins):

Zombie Chow: 1 Mana for a 2/3.
-Deathrattle: Restore 5 Health to the enemy hero.

Ancient Watcher: 2 Mana for a 4/5.
-Can't Attack.

Succubus: 2 Mana for a 4/3.
- Battlecry: Discard a random card.

Milhouse Manastorm: 2 Mana for a 4/4.
-Battlecry: Enemy spells cost (0) next turn.

Doomsayer: 2 Mana for a 0/7.
-At the start of your turn, destroy ALL minions.

Ogre Brute: 3 Mana for a 4/4.
-50% chance to attack the wrong enemy.

Felguard: 3 Mana for a 3/5 with Taunt.
- Taunt. Battlecry: Destroy one of your Mana Crystals.

Injured Blademaster: 3 Mana for a 4/7.
-Battlecry: Deal 4 damage to HIMSELF.

Dancing Swords: 3 Mana for a 4/4.
-Deathrattle: Your opponent draws a card.

Deathlord: 3 Mana for a 2/8 with Taunt.
- Taunt. Deathrattle: Your opponent puts a minion from their deck into the battlefield.

King Mukla: 3 Mana for a 5/5.
-Battlecry: Give your opponent 2 Bananas.

Pit Lord: 4 Mana for a 5/6 with Taunt.
- Battlecry: Deal 5 damage to your hero.

Venture Co. Mercenary: 5 Mana for a 7/6.
-Your minions cost (3) more.

Fel Reaver: 5 Mana for an 8/8.
-Whenever your opponent plays a card, discard the top 3 cards of your deck.

The Beast: 6 Mana for a 9/7.
-Deathrattle: Summon a 3/3 Finkle Einhorn for your opponent.

Deathwing: 10 Mana for a 12/12.
-Battlecry: Destroy all other minions and discard your hand.

Clockwork Giant: 12 Mana for an 8/8.
- Costs (1) less for each card in your opponent's hand.

Mountain Giant: 12 Mana for an 8/8.
- Costs (1) less for each other card in your hand.

Sea Giant: 12 Mana for an 8/8.
-Costs (1) less for each other minion on the battlefield.

Molten Giant: 20 Mana for an 8/8.
- Costs (1) less for each damage your hero has taken.