Strategy: Scavenging Hyena all-in. Fill your deck with cheap Beasts you can kill off and whatever else you need to clear a path, then sacrifice everything to the Hyena God in an effort to kill TLK before he ever plays Frostmourne. We're talking Kill Command, Alleycat, Crackling Razormaw, etc. Mulligan hard for a turn-1 play and a Hyena, or hope you get lucky and draw what you need that turn; if not, restart. If he plays his weapon you lose, so restart if the strategy is flagging. It can be really frustrating watching TLK Obliterate the Hyena, but it can be done this way: it took me like 50 restarts, but my father did it in 7.

Improvements: Rastakhan's Rumble introduced Springpaw and Halazzi, the Lynx, both invaluable tools to boost your Hyena and clear the way at the same time. Diving Gryphon and Mok'Nathal Lion can also work.

Strategy: Secret Cheese. You can use Kabal Lackey into Counterspell to make the fight more of a normal match, or you can use Mana Bind to steal TLK's spell and use it against him, making the fight a risk but also faster. I went the Mana Bind route, for what it's worth, and worked to win before Frostmourne was played. Build a regular Secret Mage deck around the package, perhaps with more removal to save your precious 1 Health from harm.

Improvements: Cinderstorm, Rolling Fireball, and Arcane Flakmage are decent removal. Cloud Prince can be removal or a finisher, while Ancient Mysteries makes the whole deck more consistent.

Strategy: Young Dragonhawk all-in. Similar to the Hunter's strategy, you need to buff the Young Dragonhawk as high as possible and hope he kills TLK before Frostmourne is played (I'm sensing a pattern). Buffs and other people to clear the way are what you need. Blessing of Might, Righteous Protector to block access to your Dragonhawk, Adaptation to give him Divine Shield or another +3 Attack, etc. This one took me less time than the Hyena strategy, but it's just as capable as taking forever if things don't go your way.

Improvements: Brazen Zealot gives us another growing threat to work around if necessary, making the deck potentially more consistent. Autodefense Matrix protects your Dragonhawk from harm. Sound the Bells! and Hand of A'dal can buff your Dragonhawk, while Subdue can bring a Sludge Belcher down to size.

Strategy: I'm not gonna say anything about the Priest, because the fight is a joke. Without a real Lich King "cheating spell" to worry about, you can play anything that can go the distance and win.

Strategy: Had to look up what the cheating spell was, because I totally forgot this fight. I believe I used Murlocs. See the Shaman.

Strategy: Murlocs, and more Murlocs! This fight got harder now that Murloc Warleader has been nerfed, making everything you have that much flimsier. That being said, it's still doable. Swarm the board and win before, you guessed it, Frostmourne is played.

Improvements: Underbelly Angler, Scargil, and Soul of the Murloc help you flood the board. Storm's Wrath can buff your wide board. Plague of Murlocs can remove stupid stuff like Sludge Belcher while (hopefully) still retaining your deck synergy. 

Strategy: Build a Highlander/no duplicate deck and win the normal way. It's even easier now with Zephrys the Great and Dragonqueen Alexstrasza.

Strategy: Alarm-o-Bot switcheroos. Fill your deck with big minions, removal spells, and two Alarm-o-Bots, then mulligan hard for one of the Bots. Protect him long enough to get something big on the board, then repeat. TLK tends to ignore the Alarm-o-Bot to focus on the heavy minions, but you've got the clearing spells just in case.

Improvements: Woecleaver and Gather Your Party can Recruit minions directly without using the Alarm-o-Bots. The Boomship can quickly drop a bunch of heavies. Dimensional Ripper and The Boom Reaver can summon copies of your heavies onto the field. The Galakrond package can protect your Alarm-o-Bots while leading to a big draw, making your heavies even bigger.

grumpymonk - I would stick with Maiev, because Kael'thas is a bit messy. If you have to explain it that much, it's too much.

SDhn2a - Welcome to Out of Cards :D I like Y'Shaarj the most because it connects back to his original effect and stats. Moroes seems really strange, and C'Thun doesn't really feel flavorful to me. I'm not sure what he has to do with the Schemes.

RenoLord - Leeroy the Chef is really strange, so I would go with Kel'Thuzad. You won't be able to post all three images, though, so you'll have to explain in your description that you come back with 5 Health.

HyperOrange - I love Kel'Thuzad being Freeze-related, although it would be difficult to pull off the destruction effect because your opponent's minions would thaw out first. I don't like Leeroy. I understand you can copy Chickens and whatnot to really ramp him up; I guess I just don't like seeing another huge Charge minion enter the game after the original Leeroy was removed.

Wailor - As has been said, you would need to change Harrison to include Legendary weapons from other classes, otherwise he'll only provide Kingsbane because of the way Discover works. I think Xavius is too gimmicky; I know mana gain is part of the Druid's main identity, but it still feels weird to me. I like Manastorm the most.

meisterz39 - I like Maiev, but it also feels really close to what the Demon Hunter already does. You've borrowed Kayn Sunfury's effect, and Crescent Slash is very similar to the DH Hero Power. I think The Curator is more creative as a solid Menagerie build-around card. The one problem, though, is that you need to change the name: The Curator is his original name. See cards like Deathwing and Deathwing, Mad Aspect. You also need the Hero Power to say "Hero Power" at the top, but that's a minor thing most people forget.

MenacingBagel - I know you're trying to connect to Brightwing's Heroes of the Storm iteration, but healing is supposed to be one of the Mage's key weaknesses and people will dock points for that. I think if you stick with the original version of your Trickster Brightwing, but clean up the outlying criticisms, you have a solid enough card.

TheHoax91 - I like this version of Eydis better. The Hero Power is more in-line with the original Eydis, and the mana cost seems fair. I'm not a fan of your other cards, so I would stick with Eydis.

DestroyerR - Hakkar seems really cool, and it's my favorite of the three, but it's also pretty easy to abuse him with Galakrond's horde of 1/1 Imps. I could definitely see him coming down earlier than intended because of Galakrond.

KANSAS - I like this version of Mukla even more. 5/5 connects to his original stats, and his effect with the +1/+1 connects to the Bananas. Nice work :)

Swizard - I would cut off the "Make them Legendary" part, because it is confusing and it adds too many lines of text to your card. Beyond that, I think the card is fine: it could be combo'd in a Plot Twist deck with Fel Lord Betrug or Dollmaster Dorian to get those minions back into your hand/back on the table.

Xarkkal - I like the latest Subject 9. It's a direct call-back to the original effect, while also being different enough to warrant its existence. Can't thin your deck out, but generating a "free" Christmas tree of Secrets is always fun :D

Thez - These are both much better than your original iteration of Rivendare. I think I like the Rogue version more, because it captures the original iteration's effect but in a new way. I think you could get away with the weapon being a 3/3.

shaveyou - I really like the version of Sally that links back to the original. It goes perfectly well with cards like Equality or Libram of Justice to act as a board-clear, while still being potentially good on its own.

Demon - I'll repeat what I said on Discord: I like it, just think the 4/12 stat-line is weird.

DescentOfDragonsOp - I agree with Demon, the card is very polarizing. If you're ahead already this card is a guarantee winner; if you're losing this is a death-sentence. I'm not sure it's a good idea.

anchorm4n - As others have said you really need it to say "other friendly minions" to avoid an infinite loop. A minor gripe I have is the 7/5 stat-line: I think making her a 5/5 like her original iteration earns you flavor points. Other than that, I think the idea is kind of…I don't know, obvious?

CursedParrot - I think the idea is neat, while still coming back to the original Malchezaar. 5 dead Legendaries is a high number to reach, but again it calls back to the first iteration so I don't begrudge it.

MenacingBagel - This is a major departure from the original Brightwing, but then again so was Dinotamer Brann so it's not an immediate deal-breaker. I'm not a fan of the stat-line because I think it should try to stay close to the original iteration, and I think making the Sheep tokens 1/5s is weird; all sheep-producers make them 1/1, so why stop now? I guess that's to make them more sturdy and this Brightwing less overpowered, but it's still a weird incongruity.

Inconspicuosaurus - I agree with Demon: Legendary "tech cards" are a feel-bad idea.

shaveyou - I was trying to come up with a Paladin version of Sally myself, but I gave up on the idea. I think this version is a little strange: making your opponent's cards cost more is a weird thing for the Paladin (I know Rebuke exists, but still), and attaching it to a Deathrattle is especially weird. I prefer Saraad, who connects back to his original iteration better while still being different and new

Pokeniner - While twisting Kael'thas like that is cool, making him a KFT card well before the vanilla Kael'thas card existed is very off-putting for me. Also like Demon said the Combo potential is high, wherein your opponent controlling the board suddenly becomes a detriment against them because each of their Frozen minions contributes to your cost-reduction. Throw down some Wisps or Snowflipper Penguins first, Freeze them too, and suddenly your Pyroblasts are free. The card is probably okay, but I hate Combo so I'm definitely biased against it.

Conduit - I prefer the 4-mana Millhouse if-only because I would prefer not to give my opponent access to the random spells, but I will admit that the 2-mana version better captures the persona of Manastorm. I will say that, if you go with the 4-mana version, he should be a 4/4/4 to better match his original iteration.

TheHoax91 - Obviously a much better Ice Block, but it's a Legendary so hopefully that's okay. The Hero Power is crazy-strong, though, so I'm not sure how I feel about that. My main concern is that, combined with something like Awaken the Makers, Priests would just become impossible to kill.

MrRhapsody - I agree with Conduit: I think the Medivh/Medivh Prime combo is the best one. The Mage summoning random Demons is weird, to be sure, but it connects back to Medivh's lore as being possessed by a Demon and whatnot, so it makes sense on a thematic level.