All Comments

And long list it is.

• Your Hero Power lacks "Hero Power" in bold at the top that all Hero Powers have although this is a very minor thing to point out.
• I don't like the fact that you can't use your Hero Power if you already control a Ghoul. While I know this exists for balance reasons, it does go against a principal of basic Hero Powers which is to be mostly freely usable and to never feel situational. With Totemic Call, you can't use your Hero Power if you control all 4 basic Totems, but you need to control all 4 of those Totems first.
• As for the 3 mana Hero Power, balancing a proper 3 mana Hero Power will be difficult when we lack an existing precedent, but I think it probably can be done. Unlike Demon Hunter with 1-mana Hero Power though, one problem with a 3 mana Hero Power is that it does hurt the fact that Hero Powers are meant to be relatively easy to fit into almost any turn, and having a 3 mana Hero Power makes it more difficult to do this.
• Rune Charges are a fine idea, although it's not entirely intuitive what they do from the description. They do also limit some weapon design space as you'd need to make the upgrade for each weapon you make immediately intuitive. I feel like it'll also take away from the keyword if you end up making a lot of weapons that don't work with Rune Charges.
• I'm not sure what the "Core" set is supposed to be. If it's supposed to be the Classic set, then it should have the Classic watermark. If it's supposed to be the Basic set, then the cards aren't supposed to have rarities and Rune Charge isn't allowed to appear in your Basic set since it's a class keyword.
• Mind Freeze is pretty weak. I feel like it could be 3 mana or maybe even 2.
• Forsaken Scholar is also weak. You could give it more stats, or give it Taunt.
• I don't mind the fact that Howling Hatchet is identical to Death's Bite, but if this is supposed to be the Basic set, then Deathrattle I believe doesn't appear in Basic.
• Failed Adventurer is also weak. I'd say it would be better as a 4/6, but even making it a 5/6 isn't outrageous anymore with Circus Amalgam in the game.
• Anti-Magic Zone is very weak. Compare it to Spellward Jeweler, which has a 3/4 body as well as this effect for the same cost, and doesn't see any play.
• Leeching Dagger might be able to have 2 Attack unless your class is full or hero/weapon Attack buffs, which the ability implies that it does.
• Frozen Footman should use the same wording found on Water Elemental. It's also weak, and I think it could be a 1/3.
• Frostbeard has an orphan in its textbox which doesn't look good, although this is a very minor thing to point out. It's also a bit weird to see a Pirate Legendary in what's supposed to be the core of the class since DK doesn't strike me as a Pirate class.
• Frozen Giant has 5 lines of text, which will always be unacceptable in the eyes of any professional until the end of time (or at least until Hearthstone has cards with 5 lines of text in the actual game). Can't attack shouldn't be bolded, but it honestly doesn't need it in my opinion.
• Heartwarming seems VERY slow, so I'm not sure how to evaluate it, although it takes forever to get good value of it.
• Bloodied Blade is a cool card, although it seems too similar to Howling Hatchet in your Core set.
• Vampiric Brood is… weird. Assuming I understand how passive Health buffs work, this basically makes you Immune for one Attack which seems weak for 3 mana considering Blur exists. Passive Health buffs in general are often avoided by most people due to the fact that they're very wonky to work with. Team 5 themselves has pretty much acknowledged this as they've stopped using them since way back in GvG.
• Howling Blast can probably be 3 mana.
• Frostwake seems weak now that Glacier Racer has released in the days since you made this.
• On a Pale Horse is probably weak, although it's a pretty dangerous effect, so maybe it's worth it? Kayn Sunfury makes this seem weak though.
• Freezing Elemental can be 4 mana.
• Sterner Stuff is another card with 5 lines of text.
• Chilled Challenger has Battlecry misspelled.
• Deathloc is cool, but it might be weak when compared to Shooting Star or Felscream Blast. If your class has minion buffs though, then I suppose this can counteract against this.

Sorry for the really long list.