I read somewhere that the core set will be revealed at March february 25, but I can't remember the source.

Quote From eazy

Why would I ever put the original Deathwing to my deck when this one is just strictly better? With Ysera re-work one can argue, that sometimes the original is better, but here we have a buffed version of the existing card. 

It has less/more unreliable discard synergie, so it's not a 100% buff

Well, better get used to them because they will appear in all 3 expansions this year :)

Atleast accoarding to this dev interview.

The main difference is that mercenaries will have a map where you can select where you want to go, so it's not as linear as the usual dungeon run mode. Another difference is that not everything is fight releated, kinda like bobs tavern. Slay the spire has for example ? rooms that have a random event with things like "you are falling. What do you want to do" where you have to decide which card you want to remove from your deck for example.

The actual combat on the other hand can't really be compared to anything, atleast from the informations we got.

edit 2: I found another dev Interview on Youtube:

- they confirmed that Mercenaries was originally planned as the 2. Gamemode for the Darkmoon faire expansion, but it wasn't quite ready yet

- they revealed one of Illidan's Mercenarie Artworks (5:40)

- Mercenaries will have cards ( I was honestly not 100% sure about this before the Interview because of the removel of mana and introduction of cooldowns)

- they are still "super early on in development" Note: this is a direct contradiction to the ign interview where they said that the mode has its own dedicated team that's working on it for almost a year and to the statement before that it was originally planned as the 2. gamemode for DMF.

- There will be some form of Leaderboard or mmr for the pvp version

- One of their goals was to have a better progression system than Battlegrounds (which they are also looking into)

- there will be no direct incentive to play pvp. You can play whichver mode you prefear without touching the other if you want

[not directly mode related]

- All 3 Expansions will be connected through the Mercenaries characters and their Stories.

- The mercenaries Stories will be appearent in every gamemode and not just singleplayer.

- All rank up spells will feature the mercenaries in their card art

Quote From PopeNeia

It just sounds like its shaping up to be a glorified dungeon run

Well, it's neither a rogue-like nor a deck building mode and the combat system alone differantiates it a lot from the other modes(the pve and pvp will also play differently from each other). So I don't think it's fair to say that it will just be another Dungeon run mode.

It most likely was the Mercenaries mode which they now pushed back into the next expansion.

edit: techpuls just released a new Interview with more new informations:

- There will be around 40 mercenaries at launch

- equipment will enhance the abilites (so they are not just stat upgrades)

- pvp will be optional

Ign published an interview with some informations about the new gamemode that OOC hasn't covered yet. So I thought I'd give you a short summary of all the new information:

-Mercenaries has its own 15 person dev team that is actively working on the mode for over 11 months. The dev team also includes Paul Nygen who pitched the idea of the Dungeon Run mode.

-Mercenaries was originially planned as an 2v2 mode, but they then settled on the rogue-lite (I know the devs are calling it a rogue-like, but a rogue-like with permanent progression is per definition a rogue-lite) and rpg mechanics

- they refear to the runs as "levels" (they also did that other times they talked about it)

- equipment can come from "drops in levels" or from other sources

- the max level could be level 30 ("level 1 to, say, 30")

- the endgame is about enhancing your characters and equipment

- There will be an heroic option

- some abilities will be better against certain bosses

- a lot of endgame gameplay will be about figuering out how to counter a certain boss

- Jaina and the Lich King will be bosses

- You can see what the enemy will do in the pve parts. That's not the case for pvp

- As a result the pve part will be more about puzzles, and the pvp about bluffing and playing mind games (probably not the card Mindgames )

- they announced the mode at Blizzconline to show everyone that Hearthstone is doing more than just releasing expansions.

Bonus from an GamesPredetor Interview I stumbled across:

-The mode will have no mana system and the abilites are cooldown based instead

- example abilities could be a simple attack or a Dragon breath that either deals damage, or heals an ally.

- they think that the mode will be really deep

- fights will reward you with xp and "resources"

All of this sounds super exciting and I can't wait to learn out more.

Note that this answer was given to the question if Hearthstone will ever have cross promotion skins (like Reinhard warrior or Moira Priest)

The more I hear about mercenaries the even more interested I become. Upgrading them into different versions with new and or improved effects, equipable and upgradeable gear on top of the already revealed rogue-lite pve/pvp/rpg mechanics. I can't wait for them to give us an complete overview.

I don't think so as they would need to animated each one (for clarification: only new heroes get new animations, skins of existing ones won't), the pack is probably just the reward for completing her story.

I wonder what's up with the gems over the map icons.

This probably IS the new game mode they mentioned, but they shifted it to the next expansion because they progressed slower than anticipated.

*rework. It's not a flat out nerf.

So they moved the new Gamemode to the next expansion?

Pretty risky to announce this after an Nintendo Direct and right before the Blizzconline.

I don't expect the core set to have any theme at all, as its main purpose is to give a solid foundation to build on. Besides that they already said that they won't do a connected story for a while and that the Idea of Exp1: meet A, Exp2: meet B, Exp3: A vs B has already been done in the year of the Dragon.

Quote From ElSabidon

However, the Tavern Pass is not perfect. As stated before, the first 50 levels are insanely grindy

Also, there have been a couple of posts in which the devs made about events that include XP for catching up, but we've seen none so far (though those should just arrive closer to the end of the expansion cycle, as they're being treated as a catch-up mechanic rather than extra XP for us).

They already announced that the next reward track will be twice as long while keeping the total required XP to give you the rewards more frequently. As for the event XP:

"We’ve heard your feedback: higher levels of the reward track just take too much XP to reach. We originally included event reward XP when calculating our intended cadence of rewards. We’ve rethought this and recognize that the rewards track should stand on its own and not require event XP bonuses, making rewards predictable and consistent across an expansion. We will still have in-game events, of course, but they will remain consistent with our existing approach to event rewards instead of rewarding bonus XP for the rewards track.

We’re reducing the requirements of the current rewards track by a total of 37,000 XP (nearly 20%), which will make mid-to-late levels easier to reach and adjust for the absence of XP events"

3 might be too much, I would either nerf it to 2 mana or lower the weapon damage by 1