Hearthpwn

I love the flavor of this card, and the golden animation is one of the coolest looking animations in the entire game. Great design.

New Undertaker ladies and gentlemen. Be prepared to somehow deal with a 5-heath creature on turn 3 or lose the game. Fun fun fun!

I guess they won't be lonely anymore.

One of the few good anti-aggro cards released since Naxxramas (note: when I say anti-aggro, I mean "cannot be used by aggro." Shielded Minibot is good against aggro, but it's just as good in aggressive decks as it is against them, so I don't count it or cards like it as anti-aggro). An essential card for any non Warrior or Priest deck aiming to win long drawn-out attrition games, or combo decks aiming to buy time to draw into combo pieces. This card is particularly strong in slow Warlock decks, since Warlocks use their health as a resource to gain card advantage more than any other class, and lack any class-specific heals.

"2 Mana to restore 8 Health TO YOUR HERO." That bit is important. The lack of flexibility to heal a minion like you can with spells like Lay on Hands or minions like Earthen Ring Farseer makes the card balanced. Besides, a 3/3 is only worth about 2.5 mana. A 3/4 is worth 3 mana.

Imagine Jaraxxus + Loyal Companion on Turn 10, or both those cards plus hero power if both get discounted by Thaurissan. That card has a lot of potential.

A very strong card that has seen play in pretty much every Warlock deck except Zoo. A 2-mana vanilla deal 3 damage may seem uninspiring when you compare it to similar spells like Frostbolt for Mage or Wrath for Druid, which have additional upsides, until you consider these two things:

1. In 90% of circumstances, spells like Frostbolt and Wrath, despite their potential upsides, are used as vanilla deal 3 damage to remove a minion. Darkbomb is not actually that different from these spells in the vast majority of scenarios, and these spells are considered top-tier cards for their respective classes.

2. Warlock cards usually have a significant downside to compensate for their overpowered hero power, so the fact that this card has no downside is, for Warlocks, an upside.

Additionally, Darkbomb was contextually very important for the class since it lacked good removal. Soulfire was good for aggro zoo that would dump their hand fast, but Handlock risked discarding important cards in exchange for simply killing a Knife Juggler, and Darkbomb filled that gaping hole in the warlock's lineup very well by providing a reliable early game removal spell to buy time until the Twilight Drakes and Mountain Giants.

I honestly think this card is a little overpowered. This card usually ends up dealing a minimum of 4 damage for 1 mana if played on turn 1, which is ridiculous value for an aggro deck. It's not even that bad in the late-game, since it's guaranteed to do 2 damage even if your opponent has enough of a board to kill it (unless they waste a silence on it). I've had perfect 1-2-3 curve openings against face hunter and still been at around half health by turn 4 and eventually lost because of this card and other mana-efficient high-damage cards like Mad Scientist and Knife Juggler were played before I had an answer. It really bothers me that this card and other aggro cards like Abusive Sergeant and Knife Juggler are ridiculously mana-efficient and have no downside at all, while late-game control minions and defensive cards simply aren't good enough to justify their cost. The mana system and trading mechanics of Hearthstone (i.e. attackers have complete control over what minion attacks what) already favor aggressive and tempo-oriented strategies over defensive control strategies, and aggro having access to such high-value low-cost cards with no drawback doesn't help the imbalance of power.

I disagree with your judgement on Erethral Conjurer in Tempo Mage. You say it's too slow, but Tempo Mage already plays Azure Drake, which is essentially the game thing as Erethral Conjurer (5-mana understatted minion that refuels your hand). Whether the Conjurer is better than the Drake will have to be seen (I think Drake will probably still be better due to Spell Damage +1 and better stat distribution), but Conjurer is absolutely a valid choice for that deck and will probably see some experimental play.

Nothing better than winning against Freeze Mage by stealing their Archmage Antonidas and generating 3 fireballs with Power Word Shield, Light of the Naruu, and Circle of Healing.

Yeah you can easily make legend without Antonidas. It's not the card that makes or breaks the deck. It doesn't even matter in a lot of the games you play because of how aggressive most popular ladder decks are. Ragnaros is a perfectly viable substitute.

Ragnaros. Maybe Sylvanas. Potentially Rhonin but that's probably too slow. Just a big dude that will win the game if it goes unanswered.

Rogue hero power is the best in the game in the early-game. Late-game it's bad but this is an early-game card. Rogue hero power is the one you want early game.

Nice synergy with Doomguard Kappa

I believe you usually just play them on T3. They can be pretty scary if your opponent doesn't have an answer, and if they do, they often have to spend their entire turn and a lot of resources on getting rid of it, which will give you the initiative. Alternatively, you can combo it in the late-game with whirlwind effects to make a big minion that demands an immediate answer and makes it even harder for your opponent to answer both your big Frothing and your board full of patrons. It's overall one of the better 3-drops in the game even when you can't give it charge and OTK your opponent.