Most OP hero and most OP card

[Twio]

Maybe Harbinger should only discard a card from opponent's deck?

You want to semi buff it?

How in Lord Buddha's name is that a buff? You effectively halve the probability that the +1/+1 will occur, and remove its synergy with Reactorary and Brimstone.

I don't understand the people that think the OP part is the fact that your opponent has to mill one card.

[Heidrek Rampant]

Because I consider being milled a bad thing.

Sure self milling allows some sick tricks now and again but by and large it'll mill an otherwise useful card of the opponent. Roughly the same chance of a misfire either way and is rather they mill thier MC than my Bloodfrenzy.

[jcbow]

That one card mill if not discarding from self is still a huge nerf

[Heidrek Rampant]

Having it one sided against the opponent is a buff/nerf while having it discard only from its controller is a straight out nerf.

I guess if I could have a choice if rather it was one sided against the opponent that unilateral.

[jayceemp]

but you also reduce the chance of him being a 2/4 by 50%. that's definitely a nerf

[Heidrek Rampant]

Exactly, in fact that really the only part that is a nerf. Self discard will hurt you more often than help you, but that's by the by. As it stands is rather have it mill one card ideally from its controller but I can live with it either way.

Or how about this compromise:

Mills both decks for 1 card, only gets the buff if it's opponent mills an ally.

That way if they get a brimstone or reactorary they are unlikely to get the buff as well(both would need to discard an ally).

[Markmasters]

You know every single deck in the game will toss harbinger out again and put karash in then again? At least there is some variation now....

Sure, 2-4 is decently stromg for a 2 cost ally, but champion of irum has the potential of being 3-5

[Middle Aged Nerd]

Ill tell ya whats really op. Batman. Dude invited green lantern over to a neutral site. Painted everything yellow including him and robin made lemonade and then robin punched him in the throat crushing his larynx. Thats OP.

[Alien Fungus]

Superman is the most overpowered hero. Dude can fly wrong way round the world and turn back time! He's closely followed by Martian Manhunter and Chuck Norris.

Chuck Norris doesn't come third to anybody ... The dude counted to infinity ....twice !!!

[JohnnyCRO]

@Superheroes discussion
Superman is OP; but he's an idiot too. Batman is the boss (for any unbelievers, read/watch The Dark Knight returns).

OT:
Hmm...
TBH, everything seems kinda balanced to me. Even the Harbringer; it can miss an ally and then you wasted 2cc for useless ally (well, relatively useless) and depending on its mill, it can be a major screwup (I like when playing Vic and they just mill me that Gambit... 3 ).
There are good cards and good heroes, there are bad cards and bad heroes (relatively). But in the end, there is no single hero or a single card that is so powerful that it would define the entire metagame because of it beeing too powerful.