Look, so a discussion in another thread made me make a personal tier list (with explanation of my choices) of the current Death Knights, with potential to update in the future, though considering how hard it can be to update my Highlander thread in fan creations some days, maybe not. I just want some opinions on this because I'm a little biased on some of these (I don't understand the hype of Zul'jin) and think this might be a cool discussion. Also, excuse anything that might seem a little too aggressive, I wrote this list(and the discussion post that went with it) at 2 a.m. annoyed that some guy called DK's 'infinite value' when only half fit that description (I know it's nitty-gritty, but I'm a Magic player at heart, if you guys think Hearthstone has power creep, you've ain't seen nothing yet).
Death Knights are in four tiers, one is infinite value, two is near infinite value, and three is very finite value, and four is just garbage. Tier 1 is probably the DK's I question most in their design, like why did anyone think this was a good idea, Tier 2 is DK's with powerful effects and hero powers, but they eventually run out of gas (some more quickly than others), Tier 3 is DK's that are either played for only one half of their card, as the other half has finite value and even then, the half of the card the DK is played for is not infinite value either, and Tier 4 is pretty self-explanatory, there's only one Death Knight in Tier 4 and once you see who it is, it's pretty self explanatory.
Deathstalker Rexxar: Jesus Christ this thing, what was Blizzard thinking? The ability to create a new minion each turn in already quite powerful, but to have it be a random minion that is a fusion of two random beast, each varying in strengths and abilities is insane. This is the only DK hero power that should've been more than 2 mana upon transformation, just to keep Hunter from DK'ing and then start consistently dropping 7-8 mana Zom-beasts every turn with no need to prep the turn before. This thing is the only Death Knight that should have been nerfed based on it's power alone, though the indirect of Priest's DK through Raza's nerf is a very close second.
Dr. Boom, Mad Genius: The only reason this thing is on the same tier as Rexxar is because I didn't feel like getting into the nitty-gritty with 1.5 and 2.5 tiers (It would have been ridiculous, not worth the effort). Boom is honestly a much more tame Rexxar, with a mix of card advantage, life gain, removal, and minion generation, Boom's mix of power if more balanced as you can only do one at a time, instead of like Rexxar, which can give you 2-3 of those effects on one Zom-Beast, though that usually takes up Rexxar's whole turn, while Boom can still do things afterwards. Personally, I think Rexxar is still the stronger of the two, but after The Frozen Throne rotates, Dr. Boom might become the fear of Standard again (Ah, the GvG days, good old Dr. 7...man, he seems surprisingly balanced considering all the ridiculous shit you see now).
Frost Lich Jaina: While an elemental deck is better equipped to abuse her passive, the fact that her hero power summons elementals if used properly, those elementals being one of the best 4-drops ever printed, all while giving the added effect as a (mostly) consistent source of life gain, makes her the most powerful of the Tier 2 DK's, imo. She has two glaring weaknesses though; the fact that her hero power has to get the kill in order to get the elementals and the fact that any full board clear effectively shuts off her life gain. These two make beating Frost Lich an infinitely easier task. If you can't do one of these (usually the board clear one), make smart trades, do you best to slow down their game plan as much as possible. I've one Frost Lich mirrors doing this, and I personally think that anyone who whines about Jaina being 'infinite value' is someone not thinking hard enough when it comes to this game. TCG's and CCG's are strategy games are their core, if you can't think like that, I can't do much to help with that.
Hagatha the Witch: While definitely the better of Shaman's two Death Knight cards (the Witch is incredibly more powerful than the Evolve-bot what was Thrall, Deathseer), she is not infinite. She actually requires the deck to be more built around her than any other previous DK's, while Rexxar, Boom, and Lich, can go into (almost) any deck in their respective class, Hagatha requires a minion heavy Shaman as her hero power only pumps out spells as long as you have minions to play, and even then it's not even good. Seeing multiple copies of Ancestral Knowledge, Ancestor's Call, and/or Eureka! in a single game just fills your hand with useless garbage most of the time and you need to empty your hand so you can get better cards and hopefully not overdraw. This hand filling gets even more ridiculous if you play her in Shudderwock decks, as you'd rather have your combo pieces and more Shudderwocks over a random spell of two. Her battlecry is probably one of the best battlecries of the various DK's and if I was grading them by their instant value alone, she would easily be top 3 or 4, and while the passive hero power if useful, the random junk can hurt your game plan and even put you game losing situations against certain match-ups.
Valeera the Hollow: One of the various reasons many players have a dislike of Millbane. She's probably the tamest card when it comes to Millbane's various enablers, but she is powerful nontheless. Stealth for your hero is possibly more powerful than throwing up a wall of taunts as you can't throw targeted spells over the wall, however, this effect is actually the weak side of her (imo). The Shadow Reflection is the ability that allows Millbane to play multiple Coldlights in the late game, that allows Deathrattle Rogue to throw down multiple efficient minions in a turn, and allows them to double (sometimes triple) up the use of spells and further extend combos (I've used Greater Onyx Spellstone twice in a turn, 6 Assassinates for 10 mana felt so fucking good). However, Valeera, much like Hagatha, is based on your deck, you can only go so far with her, and the second you run out of cards you can double up, you lose the power of her hero power, and with that, lose all the efficiency of the card.
Malfurion the Pestilent: I am ready for the disagreements on this one, I know Druid has been (and depending on the future, might continue to be) the bane of many people's existence, but honestly, that's more of Druid as a whole as less about their DK. Look, at instant value, Malfurion is easily top 4. Imo, he, Hagatha, Gul'dan, and Valeera are the top 4 in terms of instant value, and I'll get into while I don't include Zul'jin on this list later, but for now, realize that all the 'power' that Malfurion has is just posing to disguise the fact that the true power lies in your ability to choose, but when you break it down, you realize that very little is actually in terms of power. His battlecry is a choice between Webweave, a meh spell, and only two triggers of Spreading Plague, and while Plague itself is an amazing card, only two triggers means you're probably desperate to either empty your hand or have some taunts for immediate threats on the board. On the other hand, his hero power is a highly overrated split of Gnash, with one side being a better Armor Up, but a worse Tank Up, and the other side being 3 attack, while powerful, that's 2 mana for an Eaglehorn Bow attack each turn, those build up, but since you aren't getting the extra value a Hunter would get off of those secrets you would be theoretically popping to keep the bow in a useful state. Now I know Fandral Staghelm makes both of these effects incredibly efficient, but considering those triggers are 11 and 6 mana respectively (for just one use, playing Fandrel and then using the ability), it feels like there might be better plays than that.
Zul'jin: Hunter's Shudderwock...god this thing is a mess, look I know it's powerful, being able to replay spells in a class with very little spell generation and card draw is immensely powerful, especially with the ability to replay secrets and the various token generators that Hunter has gotten in recent expansions, but this still feels lackluster. You can't play several good Hunter cards as they are either too inefficient or have the chance (sometimes guaranteed) of hurting you more than you opponent. The paradox is similar to why you don't play direct card draw or targeted damage in Shudderwock, you end up hurting yourself as much, if not more than, you do your opponent. Also, that hero power, wtf is this Shadowform, Odd Mage, Steamwheedle Sniper, bullcrap. Like, you gave Hunter's DKs the most interesting and the most boring hero powers out of all the DKs, how, just how.
Uther of the Ebon Blade: I'm going to say this again, if I really wanted to, I could go and add more tiers, because honestly, so many of the DKs on Tier 3 (Seriously, half of them ended up on Tier 3), but the amount of half tier crap is something I do not have the patience to deal with, so instead we have the centerpiece of Exodia Paladin on the same tier as Scourgelord Garrosh. Look, Uther getting an Ashbringer with lifesteal is a great battlecry, not top 4 material, but very close, honestly, him, Zul'jin, and Anduin are all tied for 5th in my mind. The real power and weakness in Uther lies in his exodia hero power. As the first of now multiple win conditions that didn't involve dealing damage to your opponent, the four horsemen are what the upgraded Paladin hero power should've been, 2-mana every turn for a 2/2, expect that one wouldn't have exodia potential or anything like that. Unfortunately, all this talk of Uther's Exodia combo potential is also the DK's weakness, as the 2/2's are simple fodder, unlike Jaina's elementals or Rexxar's Zom-beasts, the four horsemen are taken care of quite easily and it leaves Uther with very little power outside of it being able to win you the game if you can assemble all the pieces, or your opponent is an idiot and doesn't deal with them (I've had it happen before...people are ignorant in the face of danger sometimes).
Bloodreaver Gul'dan: At some point the lord of demon's was turned into a vampire...which considering Warlock's constant need for healing effects makes sense, but still confuses me sometimes. Anyway, Gul'dan is actually Tier 1(and #1) in a discussion of battlecries alone, because, despite the sometimes extensive set up you need to get this battlecry off right, the ability to summon a board full of demons, even if they're somehow all Voidwalker, is a decent effect at worst and a monstrous board swing at best (You even summon Mal'ganis, 2 Voidlord's and several other good demons off a Gul'dan, the overwhelming power). This alone would put Gul'dan in Tier 2 if it wasn't for his hero power. Look, deal three with lifesteal is good effects for 2-mana, but when you're the class that is more likely to go into fatigue before your opponent based on your base hero power alone, that healing isn't going to be enough when you're 2-3 cards deeper into fatigue than your opponent. Now in situation where you and your opponent are on equal fatigue, this power is a life-saver, but in the situations where you're already behind, all it can do is slow the bleeding (don't worry, I'm shooting myself later for that unintentional pun). Also, one board wipe can hose everything about this DK's battlecry (especially if Mal'ganis is among your demonic horde).
Shadowreaper Anduin: Speaking of board clears that hose Bloodreaver Gul'dan, the card that got Raza nerfed (in what was probably one of the slowest nerfs in history) makes to Tier 3 due to said nerf, pre nerf, easily Tier 2, possibly making Tier 1 considering Dr. Boom and Hagatha wouldn't be out yet. First, the mass Shadow Word: Death (Is Shadow Word: Terror/Destruction a possibility for the future Blizzard) might be one of Priest's better board wipes as the class has only three board wipes that deal with large minions and both Psychic Scream and Lightbomb are not enough in certain situations, but better in others. Then there's the hero power, the specific part that got Raza nerfed, while a resetting Shadowform is useful, you had to be playing a certain kind of Priest to truly abuse this pre-nerf, and now, post-nerf, the effect is still good, but kind of lackluster in my book, I mean, I've always felt lackluster about the hero power, as there was only one way to abuse it and that deck was honestly pretty boring as hell to play, and without Raza buffing the hero power, resetting Shadowform, while not the most efficient way shoot down minions, can be decent removal, but not the best way to do it.
Scourgelord Garrosh: At the end of Tier 3 is this hunk of junk, continued proof that if a class has multiple DKs, one will be better than the other. The weapon of this DK is probably one of the best weapons ever put into this game and I'm sad that it's attached to an 8 mana mess. On one end, this is actually a decent DK, the weapon acts as a pseudo board clear and is decent damage, the hero power being a Whirlwind every turn and the mana cost means you can DK hero power of turn 10, unlike some of the other Death Knights on this list (Uther). However, your weapon loses to good minion placement, and while Whirlwind and Warpath are good cards, this hero power isn't, it's slow, costs twice the mana of Whirlwind and can't deal with most board states fast enough to matter. Look, while Whirlwind into King Mosh and Warpathing multiple times are effective board clears when you don't want to (or don't have) Brawl, this hero power is neither of those and Garrosh finds himself down here because of it.
Thrall, Deathseer: Oh don't look at me like that, y'all should've seen this coming. Look, Evolve Shaman is a cool archetype, unfortunately, it was heavily based on RNG and while the card pool was good when Whispers of the Old Gods came out, it's gotten steadily worse as more sets get printed and Thrall is the worst of the worst. Evolving by two and having the Master of Evolution battlecry as your hero power forces the theme so hard, I'm surprised every Evolve Shaman player during Frozen Throne didn't just choke on this shit. Look, most of the DK's don't need a board state to be useful, a few build their own board state on the spot, some don't even need their battlecry to be the engine they are, but Thrall requires it, as this is how evolve works, it's a tempo style of DK and if Evolve as a mechanic has taught the players anything, it's that you shouldn't rely on extreme RNG to make tempo plays. If DK Thrall had any way to produce tokens with just the card, this would at least be Tier 3, and even without Hagatha in existence, this thing would still be the worst DK just because of how it's designed, but Hagatha the Witch as a card only further cements DK Thrall as worst Death Knight, for now.
For those who just want to tl;dr this shit, here's the quick rundown(you want the reasoning, read the post fully)(Edit;12/24/18: Updated Tier list to add .5 tiers):
I suppose there are many things to take into consideration. Mana Cost: ? Battlecry: ? Hero Power: ? Also you have to validate the Heroes and DKs in order of synergy with other cards. Yes Frost Lich Jaina is great but her own cant do anything, she needs spefic types of clears in order to be effective. On contrary, Deathstalker Rexxar, Bloodreaver Gul'dan and definately Malfurion the Pestilent are just too good by their own! Thats why these cards are auto-inlcude in any kind of meta deck, because of they raw power that needs no external card synergy.
Scourgelord Garrosh should be same tier ( if not lower ) as Thrall, Deathseeker.
Bloodreaver Guldan is at least tier 2 if not higher.
Malfurion the Pestilent has always been extremely reliable and solid until the recent nerfs, so at least tier 2 for him. I would put Valeera down there at rank 3, too niche. Only worked fine in Kingsbane decks.
And Dr.Boom is tier 2/3, no way is tier 1 right now. It will be probably more valuable once rotation happens, but until then no way is tier 1.
for really long time i was thinking about some tech card could help you dump your hand in 1 turn. some effect that lets you controlly discard cards and you will benefit from it in some way. like bigger taunt. this could alsaw be a good tech for thief rogue since sometimes you get card that you cant/ dont want to play. i play thief rogou with few pirates to buff spectral cuttlass and i dont want to play other weapons to replace it. i run azalina as tech for that case but that is only 1 card. im writing bcs i saw the talk about hagatha adding too much value and it would be nice to have some sort of tech for this.
Guldan is absolute broken godlike...Its only about the early turns...if you survive enough its a free win..still dont see how it didnt get nerfed.
If you compare it to the powerlevel of other decks, or even hero powers its beyond ridiculous. I mean for 2 mana deal 3 dmg & heal 3...its like hunter & priest on steroids combined, but additionally you get a board worth like 30-40 mana with taunts and charge. Seems fair!
10 mana card with an effect worth 40 mana...hmm
Compare it to Scourgelord Garrosh...weapon 8 mana and a board clear 2 mana, which has to be triggered first and lategame mostly useless...so for 8 mana you get an effect maybe worth 8-10 mana? Ofc its trash!
From a DK like shaman you can get a lot of more worth from it, but then you need to play the way you have minions on the board, so it requires a setup.
Guldan is more like Anyfin can happen. Just do nothing for the game, trade 100% and dont give a shit since you resummon the minions anyway.
Wow I have to tell you right away that this list is a total mess.
The most obvious one for me was guldan. You are evaluating him wrong on so many levels. The hero power is insane in every scenario. First of all If you want to fatigue your opponent you will have tools to get equal or ahead in fatigue like gnomeratu, Elise or rin.
But more important this hero power is insane in the warlock class specifically. Since warlock wants to change his hero power the most of all nine classes. Sacrificing life total to draw cards is insane in the early stages of the game but at some point this becomes really bad in the control mirror. Therefore you desperately want to switch your hp and 3dmg+heal is exactly what this deck wants.
So guldan should be tier 1 in every reasonable list.
My main point is to evaluate a alternative hero in his specific class. Not in a vacuum.