When it comes to cards, Dean "Iksar" Ayala is a smooth talker. Whenever I encounter him he comes across as smart, considered, and patient. Which you kind of have to be as a senior game designer on Hearthstone's 'final design team'. His job means that he's out there in the trenches, stress-testing every single new card before it's released, trying to predict a meta that hasn't happened yet. He's also there to deal with the fallout when a card's power level turns out to be out of whack, patiently listening to the feedback from the raging pros on Twitter. Like his colleague Ryan "Realz" Masterson and his boss Mike Donais , Iksar has to be ridiculously good at card games in order for those players to take what he says seriously.

So when he talks I listen, but prior to yesterday I hadn't managed to interview Iksar formally, much to both our frustration. And as much as I like him, I didn't want to go easy when we met at the Game Developers Conference. Of course, we spoke about Hearthstone's forthcoming The Witchwood expansion, but we also talked about the cost of the game, how the final design team missed the power of Corridor Creeper, whether there'll ever be more Charge creatures, and the rumour that Dungeon Run was so successful that players bought less packs. He also revealed to me who the best ladder player of all time is according to Blizzard's data, which will likely come as a surprise.

PC Gamer: I would say the main gameplay theme of Kobolds & Catacombs was cheating creatures into play with cards like Call to Arms, Possessed Lackey and Dragon Hatcher. What would you say the equivalent theme of The Witchwood is?

Iksar: Well, we've released a pretty small package of cards so far. Of those, I think the even and odd ones are probably going to carry a lot of weight. A lot of the inspiration on the design side there came from Reno Jackson and Kazakus, where we're encouraging you to build your deck in a certain way with this crazy restriction. As a reward for that, you get something really powerful. One of the issues with Reno was that you built your whole deck around a card, and sometimes you drew it and sometimes you didn't.

There's a lot of randomness in Hearthstone, and in a lot of games, and often that's fine—but if you ever get to a point of randomness where you feel like "none of the decisions I made over the course of the game actually mattered," then that becomes a problem. When you can only build your deck with odd or even cost cards, the bonus has to be extremely powerful and consistent. So doing the triggers at the start of the game was a key difference from Reno and Kazakus, and enabled us to balance around players always having the bonus.

Image 1 of 6 Above: All the 'even and odd' cards set to appear in The Witchwood. Image 2 of 6 Above: All the 'even and odd' cards set to appear in The Witchwood. Image 3 of 6 Above: All the 'even and odd' cards set to appear in The Witchwood. Image 4 of 6 Above: All the 'even and odd' cards set to appear in The Witchwood. Image 5 of 6 Above: All the 'even and odd' cards set to appear in The Witchwood. Image 6 of 6 Above: All the 'even and odd' cards set to appear in The Witchwood.

Are there any other start of the game effects outside evens and odds?

No. I think we're going to be pretty light on that, not just in this set but also going forward. One of the big risks to those mechanics, as we did with Prince Malchezar and also with C'Thun who pops up at the start, is that they're fine as a one-off. But if you're jumping into Hearthstone games and every single time there's a different trigger at the start, it begins to feel a little bit more like Tavern Brawl.

Are there more even and odd cards we haven't seen?

There's just the four that we revealed in the video plus the two legendaries . That's the totality. We're going to have a lot of Echo and Rush stuff too, which I think are interesting mechanics.

Rush is a new keyword Minions with 'Rush' may only attack other minions on the turn they enter the battlefield.

We know that Charge has been very difficult to balance around in the past…

[laughs] Yeah.

So are you ever going to print another Charge card?

Uh… The black and white answer is yes, of course, if there's a cool design for a Charge card. But there are bunch of problems with Charge and dealing a ton of damage from hand that's completely uninteractive for your opponent. All of [the Charge card's] power level has to be balanced around "what if they go face with this?" so it becomes uninteresting to use in any other way. Cards like Leeroy are still pretty cool. The whole identity is that this is the neutral reach minion, and it's cool to have one of those, but when you have too many it becomes quite a big problem. I think maybe we would do another one, but it would have to make really make sense for a particular character.

Is there a single Charge minion in this set?

[Deep breath] Noooo. No.

Shaman is the only class getting a new hero card in The Witchwood.

One of the cards that was just glimpsed right at the end of the reveal video was Hagatha, a new hero card. Can you confirm that she's actually collectible, because I've seen some people suggest she might just appear in the new Monster Hunt mode?

Yes. We're just doing one in this set, and it's the Shaman hero card Hagatha.

Will we see similar one-offs for other classes in future sets?

I think so. When you have the initial design group, and they're like "hey, we're going to make all these cool things for this set!" we try to give them the least amount of restrictions possible. But hero cards are awesome. They went really well in Knights of the Frozen Throne. They're just a really evocative style of card and the kind of thing we want to support going forward, but we don't want to do nine per set forever.

At some point in the future it will be interesting when you have two or three per class and you have to decide which one to run, whereas right now probably every Druid deck wants to have Malfurion the Pestilent in it.

Yeah, it's a difficult problem actually because the idea that you would include multiple hero cards in the same deck—because they overwrite each other's hero power—means that I think, design-wise, we should make them so you don't want to include two in the same deck. Which is hard to do when the hero power is quite generic, as with Malfurion. That worked well for Knights of the Frozen Throne, but is not something I think we will repeat.

Every Priest already steals my Bloodreaver Gul'dan.

I've been doing that a lot lately.

With Monster Hunt mode, this time there are four heroes to pick from rather than having all nine classes available in Dungeon Run. Does that mean it's smaller?

It's more that it's different. There were more classes in Kobolds & Catacombs, but they were the hero powers you're used to. These are more condensed, so we picked four characters that felt core to the experience.

These new heroes are all based on existing classes though, right?

Sure. I think one of them has Hunter traps, but also has cards from another class. They have totally different hero powers, so they all play out very differently. They're pretty crazy and change the way you think about building your deck. A lot.

I heard Frodan on Omnistone saying he'd heard a rumour that Dungeon Run was so popular that people spent less money on packs during Kobolds & Catacombs, and that had caused some pause for thought inside Blizzard. Was there an internal concern about making it too good?

Honestly, there's probably someone out there [at Blizzard] who's thinking a lot about those business things, but personally for me, in the four years of being a designer, they've just told me to make the most fun thing, so that's what we try to do and not worry about the rest. If people are playing the game, and they're enjoying themselves, everything else will work.

Image 1 of 4 Above: The Monster Hunt mode will feature four new heroes, based loosely on existing classes but with new hero powers and cards from other classes. Tracker (Rogue) Image 2 of 4 Above: The Monster Hunt mode will feature four new heroes, based loosely on existing classes but with new hero powers and cards from other classes. Time-Tinker (Mage) Image 3 of 4 Above: The Monster Hunt mode will feature four new heroes, based loosely on existing classes but with new hero powers and cards from other classes. Houndmaster (Hunter) Image 4 of 4 Above: The Monster Hunt mode will feature four new heroes, based loosely on existing classes but with new hero powers and cards from other classes. Cannoneer (Warrior)

Something I know you do care about is high Legend ladder, and I saw you discussing the issues that happened at the start of March that also saw the ladder disabled. The esports side of things announced that players will have to log a minimum of 30 games in order to be eligible for HCT points recently. Was it the case that some people were performing better by not playing? There was talk that people were logging an 80 percent win rate and still losing ranks.

There were a lot of bugs as a result of the changeover from the old ranked system. Some people had to play one game to get to Legend, which caused weird matchmaking problems due to how the MMR carried over weirdly to the new system. This is background information, but we do a calculation of MMR based on stars that was out of whack just because we introduced so many more stars to the system, which threw the maths off. It's only to do with matchmaking between Legend and non-Legend players. So basically a lot of bugs, and unfortunate stuff that happened which we had to correct. I know our esports and business team worked together to find the solution that was best for those players.

Are you confident it's resolved now?

Yes. It's a live videogame so there's always going to be more stuff that pops up eventually, but I think it's pretty much ironed out for the most part.

With the pre-order bundle for The Witchwood you get an extra 20 packs over previous offers. Blizzard has also been giving out more packs through events, like this week's tavern brawl—is that to stave off criticism about the cost of the game ?

I think it's important you feel like you don't have to spend money in order to have a fun experience in Hearthstone

Sure. We try to deliver as much value as we can. A lot of quests are now 50 gold instead of 40 gold, and they're easier to complete. We made the change where you can't get duplicate legendaries, you'll get a free class legendary when you first log in (to The Witchwood), plus the bonus 20 packs. We're going to continue to do a bunch of different things. With Old Gods we gave away C'Thun because that made a lot of sense with that particular set, and we'll keep doing different stuff like that.

I've been playing since February 2014, how much money do you think I've spent?

I dunno. You're pretty good. Are you a free to play guy?

No.

Huh. I can't guess.

Would it shock you to learn it's £965, which is about $1,351? I'm not saying I mind, because I don't, but it does feel like quite a big number.

I think it's important you feel like you don't have to spend money in order to have a fun experience in Hearthstone, and there are avenues to build your collection… but if you want to get golden cards that's okay too. So long as you feel like you got your value out of it, then we're sort of happy about it.

I did craft a golden Bloodreaver Gul'dan recently, so am perhaps my own worst enemy. I recently went to see Valve's new card game Artifact , which is going to enable players to sell and trade cards on the Steam Market. So I could sell all my cards, or leave them to my colleague if he engineers my death…

I don't think you should put him in your will if you think that's a possibility. It sort of incentivises him.

True, true. Is card trading something still in discussion at Team 5?

Not really. I mean we discuss a lot of things all the time, like "hey, should we add a new hero to the game?" And the answer to that question is we have a lot to explore with the existing nine heroes. Should we add chat to the game…

Don't add chat.

[laughs] The point is we do revisit these questions, but for Hearthstone it's not something we're really taking seriously.

You're on the final design team, so you do the hard yards testing cards before they release. What have you done since Kobolds & Catacombs to ensure you don't have another Corridor Creeper? Brode told me that you aim to hit around 10 percent under or overpowered, but judging by the amount Corridor Creeper was nerfed it was about 60 percent off!

The final design team actually wasn't that surprised by the power level of Corridor Creeper in a deck like token Paladin.

[Laughs] It's weird to put a number on it, but sure. Clearly it was overpowered, because we nerfed it. So we agree. With that card specifically, it's always really dangerous to make cards in neutral that are powerful. The final design team actually wasn't that surprised by the power level of Corridor Creeper in a deck like Token Paladin. It's cool when you have a powerful card that goes into a niche deck because lots of things die, but the surprising part was that you could jam it in…

Control Mage?

[Laughs] Yeah. Even something like Tempo Rogue, which wasn't particularly swarmy, but it was really powerful there.

So it wasn't that you missed it, it was that you hadn't tried it out in less obvious decks?

I think the oversight was that we didn't try it [in conjunction] with many non-token cards. There are 135 cards [in a new set], and we have a lot of time, but not enough to test one card in every single possible deck. So we use our best judgment, and in this instance our judgment call was wrong on Corridor Creeper. We still want to push things, because there are a lot of dangers in being too safe. Everything ends up underpowered and nothing changes.

Go big to break the meta At the time of our interview I was bouncing between rank 1 and 2, so asked Iksar which deck I ought to be playing to push for legend. Without hesitation he said Big Priest, arguing that it's less reliant on the Barnes into Y'Shaarj high roll than I imagined. 48 hours I hit legend on the back of going 13-5 using this list, but -1 Pint-Sized Potion, +1 Psychic Scream. YMMV, but it seemed good against both Combo Priest and Warlock.

I think it was Jason Chayes who said a while ago that as a design team you need to scare yourselves.

Yeah. Keep trying stuff. Try to learn from past mistakes. And if we mess up, then nerf the cards.

We recently ran a story about the official Chinese deck tracking app which was created by NetEase as part of its partnership with Blizzard. Are there any plans to expose more stats to players in the Hearthstone client in the west?

We have very minimal stat tracking now. We have your level, what your highest arena key is, total wins… and the reason we have that is because we think it's the right amount. It's super high level stuff and there aren't menus of pages tracking how much damage you do on Tuesdays. I think a lot of players do want more data, but I don't think it's necessary for a large majority of the player base. We take the UI very seriously on Hearthstone, where if we can choose not to add another pane then we don't. One of our UI designers always used the phrase "death by a thousand cuts," where you keep adding one more thing…

Careful, we're heading into too many deck slots territory. We've all moved on.

[Laughs] Yeah, yeah, yeah.

Are there any plans to do an Arena version of the forthcoming in-game tournament mode where you get friends together and each draft a deck?

We talked about it. I think that would be sick. It's weird to say this, but tournament mode is truly going to be a beta. We're doing the barebones stuff to start out. The biggest reason for that is, even internally, when we ask what in-game tournaments should be, everybody comes back with a different answer. To include every single idea would have been a project that took years, so we really wanted to get something out right away so you could play tournaments with friends and collect feedback. I think the Arena tournament idea is awesome, just not something we're starting with.

Is ban functionality one of the first things you hope to add once it's live?

Yeah, for sure. We also talked about adding a ban to ladder—not super seriously—but that would also be an interesting thing to do.

The Void Daddy Voidlord is probably the defining card of Kobolds & Catacombs, the previous Hearthstone expansion. Cheating one of these into play early is GG against most aggro decks.

Are you worried that people are going to be sick of Voidlord in two year's time.

I am, I am. Warlock got so much stuff in Kobolds, and it doesn't lose much in rotation. We have to look at that pretty closely. Everyone gets new cards so we'll see what happens.

Given that everything you do is so data driven, can you tell who the best ladder player ever is?

There was this legend of Hearthstone. No one ever knew who he was and then he quit. His name was Dengxu . He played on NA and he was the best ladder player. He was insanely good, always top of our metrics. He played all kinds of classes. I remember he won 26 games in a row at rank 1 Legend using Shaman. It was way back during the Naxxramas era. The consistency of him being at the top of the data every single month was insane. But he stopped and I never heard from again.

So you made contact?

He was on my friends list and we talked some times. A lot of old school players, if you ask them who Dengxu was, they'll be like "Whooooooah, Dengxu, Hearthstone god." He just stopped. He was playing in beta, vanilla and Naxxramas. If you guys find him , tell him I said hey.

The Witchwood launches in April. We'll have more of Iksar's thoughts on Arena mode later this week. Check out our list of the 25 best legendary cards to craft, as voted for by the pros, here.